Road Test: Peugeot 3008 2.0 e-HDi Hybrid4 Limited Edition 5dr EGC

Hybrids are all very well, but they use petrol engines and we all know diesels are more efficient. OK, why no diesel hybrids? Simple. Diesel engines are expensive, and hybrid systems are expensive. Diesel hybrids are expensive squared.

But Peugeot thinks it has a cunning plan to simplify and cheapen. Instead of using complicated transmissions and clutches, Peugeot’s HYbrid4 uses something simple and free to connect the two powertrains’ efforts: the road. It has a straightforward 2.0-litre 163bhp diesel engine and auto-clutch gearbox doing front-wheel-drive. And an electric motor and battery doing rear-drive.

This means that people forking out the extra (likely £2,000) will get something more than just fuel savings. They’ll effectively get 4WD. That’s why the system will arrive first on the 3008 crossover, a car that until the hybrid is launched is an SUV with no 4WD option. Which is like bungee jumping without that elastic rope thingy.

Another advantage of this simple modular system is that it can go into any car with space under the boot for the watermelon-sized electric motor. The battery goes in the spare wheel well. So before long most medium-to-big Pugs and Citroens will get the hybrid option.

The 3008 HYbrid4 doesn’t go on sale for 18 months, but I had a go in a prototype, which has all the right hardware but needs some software development to knock off the rough edges as the two powertrains are brought into and out of play. For an early hack, it drives nicely enough.

Think of the benefits. The semi-auto transmission is the single-clutch kind, the kind with that super-annoying pause during gearshifts. Not in the HYbrid4, because the rear electric motor kicks in to fill the voids. And for dribbling along in traffic, the diesel will stay silent for up to a couple of miles while the electric does its thing. Finally, if you select ‘sport’, the electric motor lends the diesel a hand every time you accelerate.

Peugeot says the 3008 HYbrid4 will come in at 109g/km. That’s pretty good in itself, certainly better than any other pure-diesel mini crossover. But a Peugeot engineer did me a back-of-an envelope calculation that makes it seem even cannier. He reckoned a 3008 would need a 2.2HDI to match the HYbrid4’s performance, and a torque-converter auto to match the smoothness, and conventional 4WD (not of course available). Fit those things and you’d have something nearly as costly and heavy as the HYbrid4. And he reckons this notional vehicle would do 190g/km, compared with the HYbrid4’s 109.