Road Test: Mercedes-Benz E Class E300 BlueTEC Hybrid 4dr Auto

Do you really care about fuel economy and CO2 emissions? Does it really affect your car buying decisions? Are you really on the right website?

Naturally, an esteemed TopGear.commer won't care that this new Mercedes-Benz E-Class can record quite staggering fuel economy and emissions numbers; numbers that require capital letters. We're talking Big Numbers.

No, you will instead be concerned with the fact this new hybrid Benz will accelerate from 0-62mph in 7.5 seconds and top out at 150mph. You will also be encouraged by the news that the box-fresh 2.1-litre diesel engine, like the one you'll find in a regular E250 CDI, gets a small but potent electric motor stuffed deep inside the oily bits. Think of it as the electrical meat to the engine and gearbox's bread.

This motor, requiring just 65mm more space to snuggle in between the engine and seven-speed auto ‘box, is powered by an engine-mounted battery and produces an extra 20bhp and thus provides the diesel engine with added boost for extra acceleration. It also powers the Benz on its own at very low speeds (up to 22mph) and while you're sailing along at up to 100mph but don't require the engine.

How does it ‘sail'? When you're cruising at a constant speed on a flat gradient or decline - say, a motorway - the engine shuts off and the electric motor maintains your current speed until the battery runs out, or you need to overtake.

And it works seamlessly, just. Don't think about it too much, and it's actually a very quiet Mercedes-Benz E-Class. In fact, that motor has ironed out some of the coarseness from the diesel too. The ECU mind, is a little slow to react sometimes. Like when you're sailing and, erm, want to overtake. Fast. As you do. It takes a few seconds to wake from its slumber, punting you down the road shortly afterwards.

A minor irritation, but if you keep in mind the Benz's ambience and drive it thus, you will be richly rewarded. We're talking 67.2mpg and 109g/km which, for a Mercedes E Class - or in fact, any premium executive saloon - is pretty darned astonishing. Mercedes hasn't revealed UK pricing just yet, only citing it will be "competitive" when it comes over here by the end of the year. It goes on sale in Europe over the summer at around £43k though, and considering a standard E250 CDI starts at just over £33k (and records 57.6mpg and 129g/km), the price could be the deciding factor.