Electrically driven hybrid uses a clever variable compression engine, but doesn’t have a plug.
- Nissan’s E-Power series-hybrid setup relies on an internal-combustion engine to power an electric motor; the engine has no direct connection to the wheels.
- The series-hybrid nature of E-Power means it essentially acts like an electric transmission.
- The absence of a plug, however, means it cannot be classified as an electric vehicle.
Remember the series hybrid? Likely not, unless part-electric powertrains are a personal passion. After a brief period of popularity around a decade ago, the idea seems to have been largely superseded. Only now Nissan is determined to bring it back.
Most modern hybrids and plug-ins are so-called parallel hybrids, adding electrical assistance to the fundamentally mechanical propulsion that comes from internal combustion. The series hybrid reverses that equation, driving a car’s wheels through pure electrical power and using an IC motor to generate this; it’s the same principle as a diesel-electric railroad locomotive, although with the car engine’s output supplemented by a battery pack. The pioneering Chevrolet Volt and original Fisker Karma were two early examples of series hybrids, both allowing their batteries to be charged by plugs as well as engines.
But conventional hybrids now mostly use either CVT or double-clutch gearboxes to blend their power, while more potent PHEVs typically have de-cluchable electric motors sandwiched between their engines and transmissions. Which is why Nissan’s E-Drive system’s reversion to the series-hybrid layout is a blast from the past, it’s 1.5-liter three-cylinder engine having no direct connection to the wheels, which are driven exclusively by a 188-hp electric motor.
The difference between those two numbers is down to the third part of the E-Drive powertrain—a 1.85-kWh battery which can store energy created by either the combustion engine or braking regeneration. The pack can add assistance to the three-cylinder, or give a very limited EV-only range of around three miles. What the system lacks is any kind of charging port: It isn’t a plug-in. Nissan says that a larger battery pack would bring too much weight and cost, but it means that—despite electrical drive—E-Drive runs exclusively on gasoline, something which will deny it tax breaks in many of the European markets it seems primarily designed for.
Nissan’s E-Drive system’s 1.5-liter three-cylinder has no direct connection to the wheels, which are driven exclusively by a 188-hp electric motor.
Nissan
Nissan says that the system should get slightly better gas mileage than a similarly potent parallel hybrid, quoting a peak thermal efficiency of 42 percent—that being the amount of the fuel’s calorific value turned into actual progress. But those numbers are, as with every other internal combustion car, well adrift of the efficiency of a full battery EV, which can be over 90 percent.
Nissan first offered E-Drive in Japan, where power was generated by a relatively puny 1.2-liter naturally aspirated engine. The new system uses the brawnier 1.5-liter turbocharged three-cylinder, which uses the same variable compression technology we saw on the Infiniti QX50, with a motorized adjuster on the crankshaft to allow the ratio to be varied between 8:1 and 14:1 to maximize efficiency under different load conditions.
Explaining the official reasoning behind the system saw senior Nissan engineers treading what was obviously a very careful marketing line as the system was introduced. “We don’t describe this as an electric vehicle,” Matthew Wright, Nissan Europe’s vice president for powertrain development told Autoweek, “but it does offer an electric driving experience for those who might not be ready for a full EV yet.” In European markets E-Drive looks set to quickly replace Nissan’s smaller diesel engines, with the engine’s ability to operate at revs dictated by efficiency rather than wheel speed also giving potential benefits under ultra-tough Euro 7 emissions standards.
“It does offer an electric driving experience for those who might not be ready for a full EV yet.”
My drive took place at the same event as the limited experience of the Ariya EV, on the Jarama circuit near Madrid with the need to maneuver through various cone-marked slaloms. I drove a Euro-market Qashqai E-Drive—in the US we’re told the first E-Drive application will be in the Rogue—but the basics will be the same in all application.
Despite the lack of a mechanical connection from engine to wheels, Nissan says that E-Drive feels more natural than the gear-slurring of a constantly variable transmission. Which it does, the electrical response to the gas pedal being sharper and more direct than in a CVT hybrid. There is a brief pause between feeling this and hearing engine revs rising, power being initially drawn from the battery, but thereafter the relative levels of noise and acceleration are normally close to those you would expect with direct mechanical drive, revs even rising and falling under part-throttle loadings to give an impression of gears changing.
With no ratios to shift, acceleration is delivered without pause. But E-Drive lacked the strong launch common to EVs; on track there was a noticeable pause under even a stamped-pedal launch, the Qashqai’s power meter taking over a second to reach its 100 percent position. The unlikely challenge of a racetrack did give the chance to confirm that, despite the motor’s single speed reduction, the E-Drive Qashqai could be persuaded past an indicated 100 mph—which is more than can be said for the speed-limited Leaf EV.
The track also confirmed a major downside: E-Drive’s weight penalty. Nissan says it weighs around 440 pounds more than its existing mild-hybrid powertrain, and although the Qashqai handles tidily by crossover standards, the mass of the front end was obvious in Jarama’s tighter corners. The other unanswered question was the one of price, with no European pricing confirmed yet. For E-Power to make rational sense it will need to be competitive with conventional hybrids, despite the costs of its larger motor and battery.
I came away from the experience impressed, but not really convinced. Nissan seems to have created an electric gearbox rather than an electric car. It’s a clever, well-engineered powertrain but, on first impressions, it is hard to see what it offers over existing rival systems beyond novelty. Perhaps that will be enough.
Specifications
Nissan E-Power
Engine: Three-cylinder, 1498-cc turbocharged, variable compression, driving through electric motor
Power: 188 hp (total system peak)
Torque: 243 lb-ft (total system peak)
0-60 mph: TBC
Top speed: <100 mph
Gearbox: Single-speed reduction, front-wheel drive
Curb weight: 3420 lbs (est)
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Keyword: Nissan E-Power Recalls Old Fashioned Hybrid Technology