Fitting a ‘range-extender’ electric drivetrain into the Evora was the project that was used as the basis for building this knowledge base. Lotus says the 414E spurred it on to help develop sophisticated Synchronous Axial flux Drive Motors with integral inverters, massively improved accuracy of the motor’s torque output (from errors of 25 per cent to just 2 per cent) and new cut-off safety systems for use in an accident.
Lotus has also used the project to develop sophisticated software control systems for hybrid drivetrains and even a virtual development programme that allows it to drive virtual test cars around a virtual Hethel test track.
There are two sources of power in the 414E. A new 15kWh battery pack which weighs 250kg and is fitted into the space normally occupied by the Evora’s rear seats. Lotus is claiming a range of 30 miles on a full charge and the ability for the battery to deliver a serious slug of power when the driver demands it.
The engine/generator is the latest version of Lotus’s bespoke 1.2-litre, three-cylinder, petrol unit. It is built around a single aluminium block, with the cylinder head, exhaust manifold integrated into one unit.
Good for 47bhp, when in charging mode it runs between 1500 and 3500rpm and can consume methanol, ethanol or petrol. The generator is mounted directly on the crankshaft. This engine is used to supply charge directly to the wheel motors either when the battery has dropped to a 30 per cent charge (at which point it stops driving the wheels) or when the driver is demanding full-bore acceleration. The motors drive the wheels through a single speed transmission.
Despite the 414E gaining 377kg over the 1382kg showroom Evora, the 4.4 second 0-62mph sprint and impressive (especially for a car driven by electric motors) top speed of 133mph is a function, say Lotus, of the new battery and motor design.
What's it like?
From the outside, the 414E is hardly different from the petrol-driven original. The interior has also hardly changed, with the push-button autobox interface on the centre console used to control the drivetrain. Lotus has also engineered a useful locking ‘Park’ mode for the single-speed transmission.
The 414E pulls away very strongly in EV mode, the twin motors delivering a sense of deep-down muscle as well as being impressively linear in their delivery of forward motion. And with the heavy battery placed right in the centre of the car, the Evora’s trademark poise, delicacy and balance is hardly troubled. Press on and the range-extender kicks in to feed extra juice to the motors.
Lotus admits it has done virtually no work on silencing the engine, though it is well insulated from the car’s structure. Even at this early stage of development, the engine/generator is capable of kicking in for as little as a couple of seconds as well as more extended interventions.
While the sense of effortless electric thrust on the sodden Hethel track was quite addictive, I can quite see why this drivetrain might be seen as unsuitable for a Lotus. With no gear changing, a seamless stream of torque and, often, no engine noise this can hardly be called a engaging enthusiast’s car. But as far as pure serial hybrid drivetrains go, however, once the range-extender is silenced it could well be the best.
Should I buy one?
You can’t and you’re highly unlikely to be able to buy one in the future. Even if the 414E’s Infiniti sister car was commissioned, for example, the Lotus range-extender motor is not due to enter series production for another two years.