Achieving the impossible?
In the recent series on the Nissan Qashqai, I mentioned that the latest generation will have a third powertrain option that is so left-field it deserves its own chapter. We are told that the e-POWER version will arrive sometime in 2022 and that nothing comparable has previously been offered in a mass-produced vehicle sold in Europe. What makes it unique is that the powertrain has true petrol-electric drive, a series hybrid system with no mechanical gearbox and electric-only traction. The internal combustion engine drives a generator which charges a buffer battery. This in turn delivers power to the electric traction motor.
Nissan’s own presentation video explains the principles and components, with some impressive graphics. In Europe at least, no manufacturer provides a powertrain directly comparable, but some numbers help to indicate how it compares with Nissan’s own conventional hybrid and battery electric vehicles:
IC engine power: 155bhp, which is just 1 bhp less than the more powerful of the Qashqai mild-hybrid options.
Electric traction motor: 188bhp. That’s your limit, as the IC and electric motors cannot operate to deliver traction together. For comparison, the Nissan Leaf BEV offers the options of 148bhp and 214bhp traction motors.
CO2 emissions and WLTP fuel consumption: The mild-hybrid 2WD Qashqais’ figures vary surprisingly little across the board, whether 138bhp or 156bhp, manual or automatic, the numbers are 143g/km CO2 and 44 or 45 mpg (combined). The preliminary(1) e-POWER figures are 122g/km CO2 and 44.4 mpg (combined).
The Qashqai’s traction battery capacity is just 2kW, one twentieth of the lower capacity Leaf options. It is effectively a buffer, allowing only 2-3km of autonomous running. There is no prospect of plug-in hybrid operation, which would require a minimum of about ten times the battery capacity. Nissan states that the powertrain will continue to operate if the battery is fully discharged, although it is not clear how much the performance is impaired in this situation.
Notwithstanding the limited battery capacity, the outcome is a powertrain which replicates the experience of driving an EV: constant torque flow, stepless power delivery, the option of one pedal operation. Everything is there, but for the eerie silence. There are no range anxiety or charging issues, as the only available energy input is fossil fuel from a roadside pump. The downside is that the readily available fossil fuel is heavily taxed, the internal combustion engine burning it produces tailpipe emissions for most of the time the vehicle is running, and the ‘sustainability’ figures will not attract tax benefits or state purchase subsidies.
For Nissan, this is not untried technology. The e-POWER system was introduced as an option for 2017 Note and 2018 Serena models in Japan, with 70% and 50% take-up respectively . The 2020 Kicks also offers the e-POWER option, as does the Chinese market Sylphy. The Asian-market forerunners to the Qashqai e-POWER use the Alliance’s HR12DE engine, a naturally aspirated 1.2 litre triple. All of this has come to pass almost unnoticed beyond Japan, China, and some South-East Asian markets. The West has possibly been too EV-fixated to pay attention but, perhaps rather too late, Nissan has managed to produce, with apparent ease and considerable commercial success, something which was regarded as an engineering impossibility only a decade ago.
As befits the range-topper for the European Qashqai range, Nissan has raised the e-POWER specification with a larger and more powerful three-cylinder engine, the 1.5 litre turbocharged MR15DDT unit. It has been widely stated that this engine is a variable compression ratio type, but this does not appear to be the case. The VC engine is actually the KR15DDT unit, presently exclusive to the 2022 Rogue / X-Trail, used in a non-hybrid configuration with a CVT.
It is likely that the choice of a triple cylinder rather than an in-line four is dictated by the engine compartment width, as the IC engine and e-POWER module are in a transverse end-on configuration. The powertrain is self-contained, occupying the space which would traditionally accommodate a transverse IC engine and end-on transaxle gearbox. The only remote item is the traction battery, about the size of a fuel tank and located beneath the front seats.
The driver-machine interface is textbook EV: Standard, Sport and Eco drive modes and the option of one-pedal control. However Nissan states that the power management system has “a focus on keeping relationship between engine RPM and road speed connected.” The company may be making a virtue of necessity here, as the IC engine will not have much resting time from keeping that small buffer battery topped up. The Nissan press release also states that “Drivers can monitor the energy flow of e-POWER on the 12” TFT meter to check the system state.”(2)
e-POWER is a fascinating piece of systems engineering, but does it make sense in a European context? Many European nations are committed to ending the sale of fossil-fuel powered cars by 2030 and the continent’s major manufacturers are throwing resources and investment at battery-electric vehicles as if their survival depended on it – which it very probably does.
In Japan and South-East Asia the situation is less binary, and consumers seem more willing to try something different. For anyone who has driven a good EV, the idea of a vehicle which replicates the driving experience without range and charging infrastructure anxiety has a great deal of appeal. Maximum torque from the moment the motor is turning and the absence of turbocharger and transmission lag make for a compelling experience. Return to an internal combustion vehicle immediately afterwards and it feels and sounds like a tractor. There will be those who lament losing the sensual and cerebral delights of exploiting an engine’s power band and the sense of control achieved through stirring an oily box of cogs and cones, but they are the steam locomotive footplatemen of our times.
If the driving experience is as good as it ought to be, e-POWER should be a winner, even if the performance and efficiency advantages(3) over the mild hybrids are marginal. There are still uncertainties: performance figures have not been disclosed and, more importantly, neither have prices. The 32bhp maximum output increase will be partly counterbalanced by increased weight but, hopefully, with an extra 70Nm of torque there should be some improvement over the 157bhp mild hybrid.
Costs will matter more than performance to the e-POWER’s success in Europe. Nissan states that the e-POWER option will be sold at “an affordable price point”. Presently, the cheapest automatic Qashqai is the £29,475 158bhp Acenta Premium Xtronic. The highest priced version currently on sale is the 158bhp Tekna+ Xtronic 4WD at £38,855. If entry level for the e-POWER option rises too much over £30K, Nissan will be coming close to the prices of rival manufacturers’ plug-in hybrids, which offer fiscal and functional advantages not provided by the e-POWER system.
A GM enigma: Voltec and e-POWER compared
While they may not seem directly comparable, there is an interesting parallel between Nissan’s e-POWER vehicles and GM’s 2011 Volt / Ampera drivetrain.
Envisioned as Bob Lutz’s ‘Prius fighter’, the GM Volt / Ampera took a different approach to Toyota’s parallel / series hybrid technology. Described as a ‘range-extended battery-electric vehicle’, the Voltec system was originally intended to have electric drive only, just like e-POWER, with the 84bhp 1.4 litre Opel engine only driving the range-extender generator.
The Volt’s drive system is a clever piece of design, with a planetary gear set allowing the generator to operate as a secondary traction motor when the control system senses high power demand. Even at a late stage of development, GM described the upcoming Voltec system as a battery electric vehicle with a discrete IC engine performing only a generation function. When the patent for the Voltec system was granted, not long before the car’s launch, observers were taken aback to find out that the planetary gear train now included a third gear and clutch pack which took drive from the petrol engine directly to the transmission.
The reason for this was that, in test cycles, involving highway driving, it was found that the process of generating three-phase AC electrical power, then converting it to DC in the inverter to charge the battery, then back to AC to drive the traction motor was only 70% efficient. The ‘efficiency deficit’ was reduced to a more acceptable 15% by introducing direct drive from the petrol engine to the gearset. The Volt had become a parallel / series hybrid, although differentiated from the Prius and Honda Insight by its plug-in charging capability and much longer electric-only range(4).
Unlike the Nissan system, the Voltec design cannot operate with a discharged traction battery as the main electric motor regulates the other power sources – if it stops delivering energy to the sun gear, the planet gears will spin freely with no power going to the final drive. The Volt, as a plug-in hybrid has a much larger battery than the Qashqai; 16kWh compared with 2kWh.
Nissan’s determination to bring e-POWER to Europe in the Qashqai J12 is a bold venture, particularly as its engine range has no high combined output plug in-hybrid powertrains on offer for those wanting something heftier yet more tax efficient than the small petrol turbos present offered. Price and promotion are likely to decide e-POWER’s success.
(1) Nissan states that these numbers are ‘Pending final homologated values’.
(2) I would much prefer it if they instead paid attention to the road ahead, and even took an occasional look in their rear-view mirrors.
(3) Toyota offered a plug-in Prius from 2012, rather under sufferance as they considered that the extra battery weight compromised the overall efficiency and technical purity of their self-charging hybrid system.
(4) The 16kWh battery of the early Volts was downrated to around half that capacity to slow down battery degradation. Later Volts and Amperas had increased battery ratings, and an improved battery-only range.