THERE'S an old phrase: the devil's in the detail, meaning essentially, looking out for hidden problems.

With Mercedes' elegant coupe, the phrase could be changed to 'the success is in the detail'. That is what gives this car a real edge, despite a hefty price tag.

A hefty price tag there may be but the Mercedes' fuel saving BlueEfficiency technology fitted to most of the range also means the car soon starts to pay back, with remarkable fuel economy for such a big vehicle and carbon dioxide emissions of only 135k/km, making it a tempting business option.

That detail mentioned becomes apparent, from the swooping, curved styling and pronounced body lines with eye-catching daytime running LED lights and double louvered chrome grille of the exterior to the with clever touches inside like the central clock on the dash styled, to my eye and one or two others, to look like an expensive wristwatch.

Extra detail is added with door sill panels with stainless steel inlays and a front illuminated door handle in chrome. The rest of the cabin is the same with luxurious soft touch finish. Dials and instrumentation have a classy, sturdy feel and are mostly logically presented.

The only problem I have is with the multi function gear stalk and the gear selector where the wiper stalk would normally be. I found myself going for the gearchange when turning on the wipers. No doubt when living with the car that would not be a problem.

Otherwise the cabin is pure class with sumptuous black nappa leather seats and black ash wood gloss finish trim.

As a four seater, rear occupants have just about as much head and legroom as front occupants even with the sloping roof and can stretch out in relative comfort. Front and rear occupants have a multiple central storage unit between the seats of odds and ends.

Boot space is decent with a long, rather than deep area of 520 litres. On the road the hundreds of miles of motoring were gobbled up by the two litre diesel, which still left the car with more than a quarter of a tank and the claimed mpg of 54.3 seemed even better.

Set the car on cruise control on the motorway at maximum speed limit and it just sips the fuel, while the seven-speed automatic gearbox's changes are seamless and geared to maximum efficiency.

The seats cosset the occupants and the thick carpets and heavy soundproofing means the cabin is cathedral-like quiet with just a whisper of road noise and wind and engine noise all but absent. The ride is smooth and comfortable, especially on the motorway, while the torquey engine's pulling 201bhp power makes overtaking effortless.

Acceleration is also brisk from a standing start, but this car is more about comfort than speed - although the mighty five-and-a-half litre V8 63 AMG should satisfy most with a lust for speed. That's if you have £80,000-plus going spare.

The CLS comes with two diesel and three petrol engines available. The tested ‘entry level' model comes in at a cool £47,000-plus and with just a couple of optional extras will tip it over the £50,000 mark. It is well kitted out with all the usual electrically powered kit like windows, seats and door mirrors plus loads of other goodies like automatic headlamps and rains sensors, parking sensor and excellent sound system.

It's a bit of disappointment at the price to have fork out an extra for sat nav and heated front seats.

Mercedes is renowned for safety and kit includes  six airbags, stability control, assisted braking with flashing brake lights, hill hold, and child seat detection monitor and alerts to detect drowsiness. Yet more neat details to make this one of Mercedes most stylish efforts to date.