Mercedes-Benz's new, more fuel-efficient CLS is a car you can buy with your head as well as your heart, says Iain Dooley.

There was much scratching of heads when Mercedes-benz launched the first-generation CLS. The concept of a 'four-door coupe' was lost on most of the, admittedly cynical, motoring press. Despite its attractive looks, the general view was that it would be little more than a niche model.

How wrong everyone was. As a more stylish alternative to a traditional E-Class, the CLS proved popular with buyers seeking to project a sense of individuality – something you couldn't do with a conventional German saloon. And the CLS wasn't all show and no go.

That sweeping roofline barely impacted on rear headroom. The cabin was a world away from its E-Class donor car and offered a distinctly upmarket ambience.

In niche terms the CLS has been a success for Mercedes, with a second-generation car sporting the same, attractive sweeping profile. And while much appears familiar, there's also plenty of change. A greater focus on cabin refinement, increased engine efficiency and a closer visual connection with the SLS supercar are just some of the highlights.

The CLS might still be a car you buy with your heart but Mercedes offer a small but environmentally-responsible engine range. Fuel savings are in the double digits percentage-wise, and there's even engine stop-start on petrol models.

Realistically, diesel remains the dominant power source, and the car's six-cylinder, 261bhp 350 CDI is an impressive all-rounder. Quiet, economical and powerful when you need it to be, the motor offers all the accelerative benefits of a petrol V8 but without the drain on your wallet.

That said, if you do want a V8, the CLS 500 doesn't disappoint. While the car might ooze sophistication, provoking this mighty V8 elicits a wonderfully-mischievous growl more suited to a be-winged performance car and it's quick, too.

Recognising that diesel accounts of 90-odd percent of UK sales, Mercedes will also add an entry-level four-cylinder motor. Once viewed as sacrilege in the context of a premium car, such a decision now makes perfect sense. In 250 CDI guise expect the car to deliver around 55mpg and a tax-friendly sub-140g/km CO2 rating. At a stroke the CLS has become a rational choice for a wider audience.

A brief drive in a CLS is all the time you need to understand its appeal. Sure, an E-Class is a polished product in its own right, but the CLS adds an extra layer of luxury and genuine individuality.

With a cabin purposely designed to accommodate four adults in understated luxury, it's easy to feel slightly decadent when surrounded by plush leather upholstery and expertly-trimmed wood detailing. The central console stretches the full length of the cabin, forcibly dividing the space into four distinct seating locations. Factor in the sweeping roofline and you feel as if you're in a plush cocoon.

One other change that's obvious when you take the wheel is the way this CLS drives. As the car heads towards maturity, its ride and handling characteristics have followed suit. And the air suspension option works wonders on poor roads and helps to maintain excellent body control on twisty routes.

Add the widely-acclaimed seven speed auto gearbox and a weighty steering and you've got the makings of a driver-centric experience, but one that hasn't forgotten the needs of the other occupants. And for the really keen driver there's also the AMG-influenced Sport variant, complete with sporty suspension settings and a subtle bodykit.

Talking if kit, you can expect plenty of it on the CLS. Mirroring the E-Class, all manner of passive and active safety features are standard plus nine airbags. Even so, Mercedes has a lengthy list waiting for you, with everything from enhanced audio and navigation to even smarter safety aids.

The media love to pigeonhole cars but the CLS is a car that's hard to pin down. It's not your average premium tin box and, on paper, it should make sense – when exactly does a four-door coupe make sense?

The CLS makes sense every time you look at it and every time you drive it, though. And with the raft of changes under its skin resulting in greater fuel savings, it's a car you can easily buy with your head as well as your heart.

MERCEDES-BENZ CLS 350 CDI

Price: �49,988 (range �46,355 to �80,605)

Engine: 3.0-litre 261bhp diesel

Transmission: Seven-speed auto driving the rear wheels

Performance: 0-62mph 6.2 seconds; top speed 155mph

Economy: 47mpg

CO2 emissions: 159g/km