Contrary to what you'd probably believe, cars don't get old gradually. It is, instead, an almost instantaneous process. You'll be driving along, revelling in your 'new' car when out of the blue the realisation dawns on you that your ride isn't that new at all. In fact it's a bit creaky. You catch the car's reflection in a shop window and realise that design touches you'd held to be cutting edge are now looking a bit blousy. Mercedes couldn't let this happen to the current SL roadster Range and have instigated measures to stave off any snap descent into obsolescence.

Although there wasn't much wrong with the SL's basic shape, a design that has endured extremely well from its 2002 launch, Mercedes felt that the driving dynamics and detailing were in danger of falling off the pace and have made many changes to the latest SL, not all of them immediately obvious to the casual observer. Let's start with the bits you can see. The front end has been redesigned, although it helps to have the old and new cars side by side to see exactly where the nips have been nipped and the tucks been tucked. The front bumper assembly has been revised with three large cooling air intakes integrated, giving it a more aggressive V-shaped appearance. The fog lights have also been repositioned with chrome surrounds, visually lowering and widening the front of the car. A matte silver finished grille with three broad slats and chromed headlights complete the changes up front, while at the side there's a wider choice of alloy wheel designs. The rear view shows a redesigned light cluster with horizontal divisions between red and white clear lens sections.

"Every curve melds into the next, flop lines and swages teasing, pouring and sweeping light from one plane to the next."

The interior has also been revised with a commitment to offering the sort of quality that buyers in this sector expect. So it is that Mercedes have fitted even softer leather for the upholstery, revised the interior colour palette, added high quality embossed metal doorsills and a redesigned chronometer style instrument pack. A remote bootlid release system is included for the first time and aluminium-look switches for opening the roof. More significant news comes under the bonnets.

The SL500 ups its game from 306bhp to a brawny 388bhp, the latest V8 offering a hefty 530Nm of torque. Displacing 5.5-litres, this engine can now punt the SL500 to 60mph from standstill in just 5.1 seconds. Despite a 26 per cent improvement in the car's sprinting ability, fuel consumption matches its predecessor at 23.2mpg. Another engine that's new but which may escape the attention of some is the V6 fitted to the SL350. Whereas the old SL350 did very well with 245bhp, the latest model has a rather more luxuriant 272bhp to dispense at will. It'll also realise a 3.3mpg fuel economy benefit at 27.4mpg.

Entry-level doesn't mean slow in the case of an SL and the 350 will get to 60mph in 6.3 seconds. If you really need some apocalyptic stomp, try the SL600 for size. With a twin turbo V12 engine that cranks out no fewer than 517bhp, you'll need quick fingers on the stopwatch as it demolishes 60mph in 4.2 seconds. For a sportier drive, there's also the 510bhp SL55 AMG with its stiffer settings, upgraded brakes and a 4.6s 0-60mph time or the 65 AMG, a 612bhp monster. All SL variants are electronically limited to a top speed of 155mph and V6 and V8 models get Mercedes' excellent 7G-TRONIC seven-speed automatic transmission that will never leave you hankering for a stick and a clutch pedal.

A developed version of the ABC (Active Body Control) system that's standard on top of the Range-topping S-Class and CL models is also fitted to the SL500 and SL600 and optional on the SL350. Compared with the old model, body movements in dynamic driving situations are claimed to be reduced by up to 60 per cent, offering a flatter, more composed ride. ABC has the wonderful effect of making a very big and heavy car feel light and 'chuckable'. Re-geared steering and punchier brakes also boost the SL's appeal as a serious driving tool.

The ABC system has been designed to interface more efficiently with the ESP stability control system to avoid the stRangely artificial feel when cornering hard that afflicted earlier incarnations of this technology. Turn the ESP off and an SL will still display its lairy side. If you can overcome the mental block about treating a super premium roadster like a Mazda MX-5, the SL is extremely capable and, dare we say, fun. In the past, most sporting Mercedes models seemed to wilfully introduce impediments to the process of enjoyment, either lazy automatic gearboxes, laughably poor manual gearchanges, vague steering via steering wheels that resembled something from the Cutty Sark or woolly chassis. It appears the killjoys never got their hands on this SL's design.

Designers have a particularly clumsy term for describing a car that just works in the metal - 'front to rear cohesiveness'. The SL has this quality in spades. Every curve melds into the next, flop lines and swages teasing, pouring and sweeping light from one plane to the next. The balance between slavishly unimaginative retro styling and the preservation of traditional design cues explains some of the more contrived punctuations but the overall effect is supremely elegant. The roof mechanism has stepped forward a generation from that of the SLK, lifting or lowering in a mere 16 seconds with a panel fit only bettered by the ALVIN deep sea submersible.

With BMW's 6 Series Cabriolet offering stiff competition, Mercedes felt obliged to give the SL a shot in the arm. It now seems to have the BMW's measure in many of the key areas that buyers look for. The old SL was a very good car. The latest model looks to be something rather special.

TOP 5 SL SERIES DEALS

The results below show the top SL SERIES deals on buyacar

	Mercedes-benz SL Series SL 350 [272] 2dr Tip Auto Convertible
	ETR	Mthly £909	Saving £11,239	Price £52,646
	Mercedes-benz SL Series SL 500 [7] [388] 2dr Tip Auto Convertible
	ETR	Mthly £1,187	Saving £12,409	Price £64,468
	Mercedes-benz SL Series SL 350 2dr Tip Auto Convertible
	ETR	Mthly	Saving £5,471	Price £59,604
	Mercedes-benz SL Series SL 63 AMG 2dr Tip Auto Convertible
	ETR	Mthly	Saving £8,801	Price £93,269
	Mercedes-benz SL Series SL 65 AMG 2dr Auto Bi-Turbo (Pre-model) Convertible
	ETR	Mthly £2,430	Saving £19,007	Price £131,193

typical 9.42% APR

PCP finance quote over 48 months,  10,000 miles pa,  deposit of £1000