4WD MODIFICATIONS - TECH TORQUE
Now that both major political parties in Australia have joined the 21st Century, it seems inevitable that the future of 4WDs is electric. Unfortunately, most pollies and bureaucrats don’t understand what constitutes an ‘electric’ vehicle. Hybrids and range-extended electric vehicles will dominate the 4WD market for many years.
The European Automobile Manufacturers Association (ACEA) states:
“Electrically-chargeable vehicles (ECVs) include full battery electric vehicles and plug-in hybrids, both of which require appropriate recharging infrastructure.
“Battery electric vehicles (BEVs) are fully powered by an electric motor, using electricity stored in an on-board battery that is charged by plugging into the electricity grid.
“Plug-in hybrids (PHEVs) have an internal combustion engine (running on petrol or diesel) and a battery-powered electric motor. The combustion engine supports the electric motor when required, and the battery is recharged by connecting to the grid.
“Hybrid electric vehicles (HEVs) are powered by an internal combustion engine (running on petrol or diesel) but also have a battery-powered electric motor that serves to complement the conventional engine. Their electricity is generated internally from regenerative braking and the internal combustion engine, so they do not need recharging infrastructure. The hybridisation level ranges from mild to full.”
‘Mild’ and ‘Full’ hybrid types differ in the size of the battery pack and, therefore, the distance that can be driven on battery power alone. Typically, a mild hybrid can travel 30-60 kilometres on electric power, before the fuel engine cuts in and a full hybrid up to 130km.
All the scaremongering about “the death of the tradie’s ute” is exactly that: scaremongering. A range-extended electric vehicle or a hybrid can have the same range and independence from a charging station as a normal petrol or diesel powered vehicle.
Twenty years ago we saw the possibility of hybrid, internal combustion engine and electric-motor 4WDs, after visiting the 2002 Tokyo Commercial Motor Show. Two years later the 2004 event had hybrid vehicles featuring on all makers’ stands and Toyota, for one, declared its intentions to market hybrid 4WDs in 2005.
Since then, hybrids have sold in increasing numbers, but what is a hybrid?
Hybrid vehicles fall into two camps: parallel hybrids and series hybrids.
Parallel hybrids have an internal combustion (IC) engine, powered by liquid or gas fuel, driving through an electric motor-generator unit, to a transmission and then to a conventional axle and suspension arrangement.
Series hybrids also use an internal combustion engine, but instead of being coupled to a conventional driveline the engine drives an electric generator, which charges a battery bank that powers electric motors at the front and rear final drive units.
In both hybrid designs the battery pack is charged by the IC engine and by regenerative action when the vehicle is running downhill. Alternatively, both types can have plug-in charging, to a conventional 15-amp mains power outlet or to a higher-wattage fast-charger. Our testing of plug-in hybrids indicates that if left plugged-in to a mains power point overnight a mild-hybrid can be recharged fully.
A parallel hybrid starts from rest using a combination of the IC engine and the electric motor, or with electric power alone, using current drawn from the battery pack.
Although a typical hybrid electric motor produces only 35-70 kilowatts, the power is available instantly, without the motor’s having to rev like an IC engine does. This torque boost means that the internal combustion engine can be smaller than normal.
Once underway a parallel hybrid can drive for some distance – usually 50km – on electric power alone, after which it uses its IC engine, with the help of electric boost during periods of acceleration.
On the overrun (when the vehicle is over-speeding the engine) the electric motor acts as a generator, to recharge the battery pack. This action also produces a powerful braking effect.
When the vehicle stops the IC engine automatically shuts down, to conserve fuel and reduce emissions. When the driver presses the accelerator pedal the electric motor spins the engine to start it and the vehicle moves off. There is no need for a starter motor or alternator in a parallel hybrid vehicle.
A series hybrid has no mechanical connection between the IC engine and the electric motors that drive the wheels, so it operates all the time with electric drive. The engine is there purely to charge the battery pack that powers the electric motors.
Because series hybrids rely on electric propulsion alone they usually have a large battery pack and are consequently heavier than parallel hybrids.
However, the series hybrid is the basis of what will probably be the ‘bridge’ between full-electric vehicles and today’s internal combustion (IC) engine powered vehicles.
This ‘bridge’ is a vehicle type known as a Range Extended Electric Vehicle (REEV). In an REEV 4WD a battery pack powers front and rear electric motors and the battery is charged from mains power when available. In the event of low battery power a small IC recharges the battery as the vehicle continues to drive.
That auxiliary engine can be an IC or a fuel cell.
Why hybrids at all
In the 4WD world the parallel hybrid
was the first choice of those makers that built hybrids. Toyota’s Kluger parallel hybrid was based on the Prius design and Toyota’s FTX future truck concept was also a parallel hybrid.
There’s no doubt that hybrid vehicles are more complicated than existing machinery, so why did vehicle makers bother with them?
Emissions and economy are the main drivers.
Today’s engines already have a plethora of emissions gear on them and they’ll need more to meet Euro 6 restrictions. Multiple computers, variable valve timing, exhaust gas recirculation, variable nozzle turbochargers, high-pressure injection, particulate filters, selective catalytic reduction and catalytic converters are complications that yesteryear’s engines didn’t need.
But even this sophisticated technology wasn’t enough to meet Euro 5 emissions round without some economy and driveability trade-offs and that’s where hybrids came in – at least for some vehicle makers.
By adopting a parallel hybrid design vehicle makers could engineer out some of the undesirable operating characteristics of the internal combustion engine – idling pollution is an obvious one – without sacrificing driveability or economy.
Electric motor boost allowed a smaller IC engine to be used, without any performance penalty.
As some form of compensation for its complication a hybrid 4WD has advantages over a conventional 4WD: city economy is better, so it needs less tankage; electrically reinforced engine braking is stronger than engine braking alone; electric traction alone is possible, if the engine stalls in a creek crossing; and electric power from the battery pack is much greater than that available from a conventional dual-battery system.
Hybrid vehicles were seen as the quickest way for US automakers to lower their corporate average fuel economy figures (CAFE). This miles-per-US-gallon target was imposed by the National Highway Safety Administration and signed into law. Trump got rid of it, of course, but it’s back again.
CAFE is designed to reduce the average fuel consumption of new vehicles in a series of incremental steps.
Some of the hybrid 4WDs on sale in the USA from 2009 struck a genuine economy chord – Ford Escape Hybrid and Toyota Highlander Hybrid – but others seemed little more than disguised ways to continue the American Dream.
The Highlander Hybrid had a V6 petrol
engine and two electric motor-generators, plus an on-demand 4WD driveline and fuel consumption claims of 27 highway mpg (9.3L/100km) and 35 city mpg (7.14L/100km).
The Ford Escape Hybrid AWD had a 2.5-litre, 16-valve, Atkinson Cycle petrol engine, linked to an eCVT (electronically controlled, Continuously Variable Transmission). The electric motor was a 70kW unit, powered by a 330-volt, sealed, nickel-metal-hydride (NiMH) battery. The battery was sandwiched under the boot floor.
The Escape Hybrid’s combined petrol/electric output was 132kW and 207Nm. If this looks a tad light on, remember that electric motor power and torque are produced from zero revs.
Canadian tests delivered 7.4L/100km on the open road and 7.0L/100km around town. If this seems odd, remember that hybrids typically get better fuel economy around town than they do on the open road, because there’s more electric motor use and more regenerative charging.
Proper 4WD hybrids
The only proper 4WD wagon hybrids in Australia are Land Rovers and Range Rovers, but there’s plenty of experience with large 4WD hybrids in the USA, going back a few years.
While sensible hybrid motoring was available in North America, the Good Ol’ Boys needed to be kept happy. There was a loophole that allowed pickups to slide into the light-truck CAFE classification, which has more generous mpg targets than passenger cars and SUVs.
The 2009 Chevrolet Silverado 1500 Hybrid
was a big crew-cab pickup, powered by a six-litre V8 and a pair of 60kW electric motors, for combined grunt of 280kW.
A 300-volt, nickel-metal hydride battery pack was charged from a regenerative braking system during deceleration and a cylinder-deactivation function turned the large V8 engine into a four-banger under light loads.
The Atkinson-Cycle engine, with delayed intake valve closing, shut down when the vehicle stopped. On normal take-offs the GM hybrid had full-electric operation.
GM’s electrically variable transmission (EVT) used two electric motors and four fixed ratios in a planetary gearset. The combination produced infinitely variable ratios between low and high.
At low speeds the first electric motor drove the vehicle, using battery power, up to 45km/h, or two to three kilometres, depending on charge level. At higher speeds, the second electric motor, at the back of the transmission, worked with the fixed gears to create an electronically variable transmission (EVT).
The grunty petrol engine kept the vehicle in V4-mode longer, by providing a constant torque level for the transmission to manage.
The Active Fuel Management System that controlled cylinder shut-off also used electric boost to let the Hybrid spend more time running in V4 mode, to maximise fuel economy.
To offset some of the added weight of the Hybrid’s driveline, the front lower control arms and propeller shaft were made of aluminium. GM had to develop hydraulic bushes to attach cab to frame, damping vibrations excited by the addition of a 70kg battery pack.
The same hybrid powertrain was used in other large GM products: the Cadillac Escalade Hybrid, GMC Yukon Hybrid and the Chevy Tahoe.
GM claimed 20/20 for its large hybrids: 20mpg around town and on the highway, or 12.5L/100km in our-speak. However, real-world testing showed these claims were somewhat optimistic. Separate tests, on different GM hybrids, on both sides of the USA, recorded averages nearer to 17mpg, or 14.7L/100km.
Over at a reborn Chrysler it was pretty much the same story: the 2009 Dodge Durango Hybrid Limited 4WD and its Chrysler Aspen Hybrid Limited sibling were both large, three-tonne, eight-passenger, full-time four-wheel drives with Hemi V8s and two-mode electric drive systems.
With twin, 65kW electric motors and 300-volt, nickel-metal hydride batteries these mothers had combined output figures of 290kW and 520Nm and were rated to tow 2.7 tonnes.
The USA’s flirtation with hybrid pickups ended in 2013, mainly because the incremental seven to 11 grand price tag was viewed as excessive by the market – particularly when the USA’s shale oil ventures forced the price of OPEC oil to collapse and pump prices in the USA dropped to less than 50 cents per litre.
However, there’s renewed interest in petrol hybrids over there, following the VW diesel-emissions debacle that has turned many American buyers away from diesel pickups.
Another factor is the emergence of plug-in hybrid electric vehicles (PHEVs) that have more electric power and battery capacity, with the ability to mains-charge the battery pack overnight.
Our testing of the softroader Mitsubishi Outlander showed the advantages of this design.
2018/19 US initiatives
Fiat Chrysler Automotive restarted the hybrid pickup trend, with the 2018 Detroit Motor Show introduction of an eTorque hybrid powertrain as standard equipment on all MY2019 Ram 1500s that were powered by the 3.6-litre Pentastar V6 petrol engine.
It was the hybrid system used in the Jeep Wrangler – a 48-volt mild-hybrid setup – that’s makde its way into the new light-duty Ram pickup. The V6 with eTorque put the Ram close to the magic 30mpg (US) mark, or around 8L/100km.
Rams fitted with the 5.7-litre Hemi V8 had cylinder deactivation as standard and eTorque was optional.
The 48-volt battery pack powered a belt-drive motor generator unit to enable start/stop and brake energy regeneration.
The system brought some extra torque to Ram models: 130Nm with the Pentastar V-6 and up to 170Nm with the Hemi V-8.
At the lower GVM end of the US pickup market Honda revealed at the Detroit auto show that it was adding a dedicated hybrid model to its light truck lineup in 2018
Takahiro Hachigo, the automaker’s president and CEO, announced that the new hybrid Ridgeline pickup will be manufactured in the USA as part of the Honda Electrification Initiative, which calls for the expansion of the company’s electrified vehicles.
“Half of the all-new models Honda will launch in the United States in the coming two years will be electrified vehicles,” Hachigo said. executive said it would begin to use the company’s two-motor hybrid system that powers cars, in its light trucks.
Currently the two-motor hybrid system is employed in the Accord Hybrid, a midsize passenger sedan which uses a 2.0-litre Atkinson cycle four-cylinder engine and two electric motors that produce a combined output of 160kW. The Accord’s 5L/100km city rating makes it the most fuel efficient midsize car in
At the 2018 Detroit Show Toyota premiered a hybridised 2.0-litre engine. This new petrol four-cylinder Dynamic Force Engine relied on a more
efficient combustion process and benefitted from a variable control system. Thanks to a higher thermal
efficiency (41 percent in hybrid models), it generated more horsepower and torque while meeting the most stringent exhaust regulations.
Output was 107kW at 6000rpm and 180Nm at 4400 rpm, plus undisclosed electric motor inputs.
This hybrid powerplant was released against the background of comments made by Toyota’s European executive vice-president Didier Leroy at 2018’s Tokyo Motor Show that there would be no more diesel Toyotas released in Europe.
In addition, Toyota engineered two new 4WD systems, one for gasoline-powered cars and the other tailored to hybrids. The former, called Dynamic Torque Vectoring AWD, worked by independently distributing torque to the left and right rear wheels, depending on the driving conditions.
The latter, known as E-Four, boosted total torque channeled to the rear wheels by 30 percent compared with existing hardware.
In front of these 4WD systems were two new TNGA powertrains: a 3.5-litre V6 (2GR-FKS), and, a 2.5-litre Dynamic Force four-cylinder Toyota Hybrid System II with 650-volt electric motor (A25A-FXS) and Continuously-Variable Transmission (CVT).
In June 2019 we drove the new RAV4 Hybrid, powered by the 2.5-litre engine and were most impressed with its performance and economy. With a claimed 163kW combined output from petrol plus electric power plants and combined torque of 440Nm, the little RAV4 was a sparkling performer and probably had enough grunt for that powertrain to replace the 2.8-litre turbo diesel in the Prado and HiLux.
We estimated that the 3.5-litre V6 hybrid package would have enough pulling power to replace the V8 turbo-diesel in the 200 Series wagon, but in 2022 Toyota/Lexus came up with a new 2.4-litre four hybrid package that outpowered and out-torqued the V6.
The much less powerful RAV4 Hybrid started off most times on battery power alone and the petrol engine cut in during acceleration. From then on it was difficult to tell which engine/motor was doing most of the work, because progress was almost silent. The CVT transmission shifted almost imperceptibly and was indistinguishable from a torque-converter auto box.
Performance was excellent, with smooth response at any speed and very brisk acceleration from the combined IC/electric powerplants when the accelerator was floored. Despite not having the economy advantage of a plug-in hybrid the RAV4 returned a very impressive 6.2L/100km economy figure in combined highway and town driving.
Here’s how Toyota’s Hybrid System II worked:
The next step
It’s unlikely that the new breed of global hybrid 4WDs will go down the US heavy pickup path. It seems much more likely that the future lies with PHEVs and range-extended electric-drive 4WDs (REEVs).
Current REEV city cars have a smaller battery pack than an EV and an IC motor to recharge that battery pack. The ‘range extending’ IC engine is smaller than that of a PHEV and operates in an optimum, low-emissions rev band.
Expect to see a plethora of REEV city cars and SUVs in the next few years.
In the truck arena REEVs are already operating as buses and refuse collectors in the USA and the Nikola One and Two REEV on-highway trucks were previewed in December 2016.
Change is coming to the diesel world and it’s happening faster than many think.
Already, nearly all European car makers have decided they’ll abandon sub-two-litre turbo-diesels within the next few years, because the costs of exhaust after-treatment equipment to comply with Euro 6 and Euro 7 are simply too great to justify.
Larger diesel engine viability may also be under threat from tightening emissions laws and projected on-road compliance testing at mileages out to 160,000km. Vehicle makers are wary of possible fines and adverse publicity, should they not meet these harsh criteria.
The well documented maintenance issues with modern diesels have vehicle owners very concerned: plugged EGR valves and oil-coated intercoolers; sump oil diluted by unburnt fuel from DPF regeneration cycles; oil starvation caused by sludge-blocked oil pickups; failed injectors and common rail pumps caused by fuel quality that’s just fine for older engines; turbos with bearings ruined by PCV contamination; high replacement costs of EGRs, DPFs and CATs; the need for AdBlue top-up… the list goes on.
Clearly, the band-aid ‘fixes’ for diesel emissions that rely on exhaust recirculation and after-treatment aren’t working to owners’ satisfaction. However, there’s no alternative to the diesel yet – or is there?
Hybrid and electric trucks haven’t exactly taken the market by storm, but there are alternative range-extended electric trucks emerging in the northern hemisphere that may change the face of road transport.
Initial REEVs will probably have IC engines, such as the BMW motorcycle engine used in the BMW i3 and the small rotary proposed by Mazda for its forthcoming REEV range.
Toyota and Peugeot trialled free-piston engines that don’t need a crankshaft.
Interestingly, the US military is also testing a hydrogen fuel-cell REEV Colorado ute.
Those who think that there’s no future for the electric vehicle should note that China made two million of them in 2018 and six million in 2022.
When Tesla opened the order books for its $US35,000 Model 3 2018 electric car in late-2016 the company received 276,000 orders on the first day! Tesla’s Model Y was the world’s largest-selling single model in 2022 – outscoring Toyota’s Corolla.
Way back in 2012, automotive R&D company Ricardo attended the Cars of Tomorrow Conference, held in Melbourne. Ricardo’s technology and innovation officer, Professor Neville Jackson, gave Conference attendees a projection of how this independent, but highly influential, vehicle research and development company saw the future.
ICs remain a key part of the company’s strategy.
Before getting into the mix of solutions Ricardo envisaged, Professor Jackson talked delegates through the Gartner Hype Cycle as he saw this famous curve applying to the automotive R&D industry. We remember the initial excitement over insulated ‘adiabatic’ engines, electric vehicles, hydrogen propulsion and fuel cells, homogeneous charge combustion engines and biofuels, but reality is far less than initial PR suggested.
Neville Jackson pointed out that Ricardo saw no ‘magic bullet’ to solve the global transport energy crisis: just hard work and persistence.
In the short term, Ricardo saw growth in downsized and boosted-induction ICs with low-speed torque enhancement, stop/start functions, friction reduction, advanced thermal systems, micro-hybrid, plug-in hybrid and electric vehicles.
In the medium term, to 2025, the forecast
was for more extreme downsizing to two- and three-cylinder engines, with combined turbo-supercharging, 48-volt micro-hybrids, plug-in hybrids in premium and performance vehicles, electric city vehicles, lean-charge stratified combustion systems and low-carbon fuels.
Looking out to 2050, Ricardo expected that plug-in hybrids would dominate, backed up by very high specific-power ICE range extenders, more low-carbon fuels, exhaust and coolant energy recovery, and advanced thermodynamic engines with possibly split-cycle and heat-pump designs.
In another crystal-balling exercise Ricardo did for the UK Auto Council there was hope for energy storage breakthroughs to power full-hybrid and plug-in hybrid vehicles, by 2025, with a hydrogen storage breakthrough to power fuel cell electric vehicles by around 2030.
Professor Jackson’s forecast seems to be accurate, so far, but the 2015 diesel-emissions scandal fast-tracked the hybrid situation. That emissions fraud by VW and subsequent European testing that showed all brands of diesel cars actually failed Euro 5 testing – let alone Euro 6 levels – have seen vehicle makers around the world move away from diesel development and bring forward their plans for electrification.
Straight electric vehicles, charged from
mains outlets, are already operating around the world and European makers have recently combined forces to increase the number of outlets across the EU.
Norway has 80-percent of its new car fleet as electric vehicles and intends to ban the sale of new cars with only IC engines from 2025. Holland looks like following this lead.
However, no-one believes that pure-electric 4WDs could fill the role of IC-powered ones in Australia: to replace the straight-IC-powered 4WD we’ll need PHEVs and REEVs.
Mitsubishi promised a PHEV Triton for release in 2016 (pic above), but now that Mitsubishi Motors is part of the Renault-Nissan Alliance that didn’t happen.
Mazda announced in 2018 that it would develop range-extended EVs and filed a patent for a specially modified rotary engine. The range extender rotary engine is designed to be mounted horizontally and is fitted with oil injection to ensure tip seal lubrication in this position.
The Chinese Haval corporation released
a PHEV powertrain in February 2017.
The Haval plug-in hybrid powertrain combined a 1.5-litre turbocharged petrol engine with an electric motor and transmission, and delivered 200kW and 450Nm, with claimed 2.1 litres/100 kilometre claimed combined cycle economy.
It was showcased at the Beijing Auto Exhibition in the HB-02 concept vehicle and began production in 2018.
The Haval plug-in hybrid powertrain offered three operating modes. In Pure Electric mode, drive was provided solely by the electric motor. The 95kW/278Nm motor was fuelled by a 13 kilowatt/hour battery, providing a range of 65 kilometres while producing zero emissions.
The Haval battery could be recharged in about four hours from a standard household power point and used regenerative braking system to charge the battery while driving.
In Power mode there was instant response
from the electric motor, with the petrol engine maintaining acceleration. The Haval plug-in hybrid accelerated from zero to 100km/h in around nine seconds.
The default mode was Hybrid Drive, which was designed for everyday use. The vehicle automatically alternated between drawing power from the 1.5-litre direct injection turbocharged engine and the electric motor to deliver the best overall fuel consumption.
The following video shows how it works:
Electric US pickups
The USA’s Workhorse Group unveiled
a working prototype range-extended electric pickup at the Advanced Clean Transportation Expo in Long Beach, California in April 2017.
The Workhorse W-15 had 320kW of power and 130-kilometre range from its lithium-ion battery pack. The range could be extended by automatic operation of a two-cylinder BMW petrol engine that charged the batteries on the run. Total range was said to be around 500km.
All-wheel drive was a standard feature as well as active safety systems that included collision alert with automatic braking and lane-departure warning.
The truck had a composite body with carbon fibre panels. The prototype was the most popular US pickup configuration: double cab with a 2.5-metre-long cargo tub.
A bonus from the on board electricity supply was a 7.2kW power system that allowed tools to be plugged directly into the battery power source.
It had 300mm ground clearance, payload of one tonne and towing capacity of 2.5 tonnes.
The W-15 incorporated a version of the E-Gen electric technology already used in the company’s medium-duty truck designs and could recharge by plugging into standard J1772 stations.
The Workhorse W-15 electric truck was said to be first in the pickup segment built in the USA.
Rivian is another player in the electric vehicle market, but this company has been quietly going about development of an electric SUV and a ute for the past 20 years.
Rivian has taken over a former Mitsubishi car plant in Illinois.
The reveal at the November 2018 Los Angeles Auto Show coincided with opening of the company’s order books and US-market deliveries have been happening since 2020.
Rivian vehicles are designed around a purpose-built platform chassis that is, in effect, a stressed battery box. Battery packs are available in 105kWh (370km range); 135kWh (480km range) and 640km range) sizes.
Battery charging can be done at 160kW fast-charge stations or home- and depot-based 11kW overnight chargers.
Drive is via four wheel motors with a combined power output between 300kW and 560kW, so performance isn’t an issue. The Rivian is claimed capable of a 0-100km/h time around three seconds, with a top speed of 200km/h.
Claimed payload of the Rivian R1T ute is only 800kg, but towing capability is five tonnes, so it seems to be aimed at the USA’s town-pickup and towing market.
There is a front bin, plus a transverse bin behind the rear seats, in addition to a 1400mm-long cargo tub.
Air suspension at all four corners means the Rivian’s ground clearance can vary between 240mm and 360mm.
“The R1T will launch with a robust hardware suite with multiple modalities including camera, lidar, radar, ultrasonic and a high precision GPS coupled with high-definition maps,” the company’s press kit said.
“This hardware enables ‘Level 3’ (hands off the wheel and eyes off the road) autonomy for highway operation.
“Beyond the highway Level 3, the vehicle will have a range of self-driving features focused on enabling active lifestyles.”
The first release was the ute, which had a RRP around US$70,000, less federal and state tax incentives for EVs that chipped up to 10 grand off that.
Yes, even Trump’s USA had EV incentives, as do many developed countries, but not in coal-addicted Australia, of course.