Mazda 2 Rotary Range Extender EV Prototype Tested In Japan

Rotary engine fans are waiting for news from Mazda about the future of the piston-less engine but the Japanese manufacturer however, has used its signature engine on the Mazda 2 Range Extender EV Prototype for a new reason. We were lucky enough to be given a chance to do a very short test drive of the car during the Mazda 3 Hybrid test drive in Japan.

Range extenders are one of the solutions to overcome the ‘limited range’ problem that deters many from buying electric cars. Typically, a range extender is a small petrol or diesel motor that charges the batteries, which in turn provide juice to the electric motors. An example would be the BMW i3, which offers a motorcycle engine as a range-extender option.

330cc Rotary Engine Range Extender

The Mazda 2 Range Extender EV prototype is based on the Mazda 2 EV electric car, which was leased to almost 100 customers since 2012. This new prototype is a further development of the 2 EV, which now packs a compact rotary engine under its rear boot floor, without losing any boot space of the regular 2013 Mazda 2 hatchback.

In order to maximise space and reduce vibration, Mazda has fitted the range extender sub-assembly, which comprises a 330cc rotary engine, a fuel tank, and a generator in a horizontal layout. The sub-assembly is really compact and weighs only 100kg together with the frame. Because the weight is evenly distributed, the Japanese manufacturer used softer engine mounts to absorb any vibration.

The single rotor 330cc petrol engine, which is designed to run at 2000rpm, outputs a modest 26hp, and is used to charge the lithium-ion batteries. This petrol engine is programmed to kick in at a low 10km/h and run continuously. The battery pack is fitted on the hatchback’s main floor, while the engine bay houses an electric motor, a controller and a regulator.

The Mazda 2 EV goes for 200km on a single full charge. With the range extender in place, Mazda claims the new prototype goes double the range of the EV with a 10-litre fuel tank. Other details such as emission figures are not released as the car is still in early prototype stage.

How did it perform?

During our admittedly short drive, the prototype gave us a good impression of what could be coming out of Mazda’s doors in the future. The new powertrain idea as a whole was impressive. Like other electric cars, the power delivery was quiet, smooth and instanteneous from a standstill.

The throttle pedal response good and refined. Thanks to good calibration, the 100hp electric motor’s acceleration was linear. Moreover, the brake pedal provided good feedback, without producing the unwanted sudden stopping feel due to its strong brake regeneration effect.

The range extender rotary engine kicked in at 10km/h, producing but a hum which is similar to that of a fridge compressor. The noise was less noticeable at the front of the car. But once the car reaches 35km/h and beyond, the engine noise is drowned out, replaced by road noise that fills the entire cabin.

Although stiffer springs are used to counter the weight of the electrical equipment, the weight distribution is still not fully sorted out. The rear feels heavy as a result of the range extender module, while the steering and chassis exhibit signs of imbalance due to the arrangement of the batteries.  But since this is an early prototype, we expect that these little problems will be rectified in the upcoming development stages.

As of now, the Japanese carmaker has no plans of putting the Mazda 2 Range Extender EV into production. However, there is a chance for the next-generation 2 to be offered in this guise, as the all-new 2 will have similar dimensions as the current 2. For now, according to Mazda engineers, the rotary engine range extender prototype is fitted to the Mazda 2 just to test the concept of using a rotary engine as a range extender. We don’t expect Mazda to be entirely open and transparent with their future plans, do we?