What's this?

It's the C350e, the second car in a 10-vehicle plug-in line-up that Mercedes will unleash on the world between now and 2017.

Headlined, perhaps unwisely, by M-B as its Hybrid Offensive, this attack on the plug-in market started with the S Class Plug-In Hybrid and will reach through the Mercedes range to include models of all shapes and sizes. It's mostly targeted at the US, where hybrids not diesels are the preferred fuel-saving engine. But it's coming here, too.

What's the news about this car?

The first bit is that, as part of its re-naming of all the models and derivatives, Mercedes has stopped shouting that it's hybrids are PLUG-IN HYBRIDs and instead just given them an 'e' badge.

What haven't changed are the official figures promising astonishingly low fuel consumption and emissions, combined with healthy performance. The C350e's vital statistics are 275bhp/600Nm with 2.1l/100km and 49g/km of CO2.

How does it do that?

By mating a 2.0-litre four-cylinder petrol engine to a 60kW electric motor, then adding a list of other refinements that offer a high level of complexity. You don't so much drive the C350e as pilot it.

Apart from the five transmission modes there is also a choice of four operating rules that allow the driver to choose the level of the electric motor's intervention. The sensible thing to do is stick it in Hybrid mode and leave it there.

Any other tricks?

Several. The car talks to you via the new haptic feedback throttle pedal. In the same way lane departure warnings buzz the seat and pulse the steering wheel if you get offline, or don't see a car in your blind spot, the C350e's pedal gives you feedback on how to save fuel.

In electric-only mode it builds pedal resistance when you are about to summon the petrol engine. It also gives a double impulse through the pedal when the radar reckons you can switch off the engine and coast to save energy.

What's it like to drive?

At town speeds, in full electric mode, the standard air-suspended C-Class rides and drives superbly. Smooth, silent, responsive, it feels every inch the mini-S-class it wants to be.

But get out on the open road, ignore that building throttle pedal pressure to get more performance, and the calm is broken by the droning petrol engine. At that moment, the car loses all its luxurious feeling and you are left wondering why you'd shell out serious exec money for this sort of noise.

To be fair, there isn't another hybrid system that uses a four-cylinder engine that is any quieter than this one. But we expected Mercedes to set new standards in sound control here, and, to be frank, it doesn't. Sound processor anyone?

But is it any fun to drive?

Fun isn't the word this C-Class was designed around. Intelligent efficiency was its mission and it meets that aim on all fronts. It's perfectly wieldy on all types of road, sips fuel, has a sumptuously comfortable cabin - possibly its best feature - and doesn't offend visually in any way. So job done.

Should I buy one?

Depends completely on your lifestyle. If you live on the edge of a city and spend a lot of time in or around towns, you'll love this car, which is available in sedan and estate formats. It will save you a fortune on fuel, tolls and even parking costs.

But if you spend a lot of time in the country or ploughing a furrow on the motorways and A-roads, there really isn't much point. You're still better off with a pure diesel.