According to AutoExpress, Subaru is working on a diesel version of the Impreza WRX STI. It will be powered by a 2.0-litre flat-four cylinder boxer unit that delivers 148 hp. A tuned version with 180bhp could be used in a racy STI version.

The engine delivers a peak torque of around 400Nm – up 50Nm on the petrol engine – and the high-performance model could sprint from 0-60mph in seven seconds and accelerate on to a top speed of 140mph.

The diesel version of the Impreza WRX STI will have a fuel economy of around 45mpg. The powerplant weighs no more than the current version, and would also help slash the STI’s emissions by nearly 40 per cent, from the petrol’s 243g/km to about 155g/km.

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