THE four-seater, soft-top Cabriolet completes the range of Mercedes-Benz E-Class models, just in time for summer.

Following the launch of the highly successful saloon and Coupe last year and introduction of the Estate earlier this year, the Cabriolet comes with some ground breaking technology as well.

Mercedes-Benz engineers decided on a soft-top hood to save weight and for ease of stowage but they did not compromise on capability to provide all year round refinement.

At first glance, the new E-Class Cabriolet looks like its predecessor four-seater two-door model, but for the new model the designers and engineers have come up with an ingenious Aircap system.  

Pressing a button raises a slim aerofoil on the front of the header rail to push the airflow over the open cabin and combined with a simple draught-stop panel in the rear it produces a positively balanced warm air chamber when the windows are raised.

Air turbulence is virtually non-existent and the system works up the car's maximum speed.

Added refinement comes with a modified version of the Airscarf seat mounted warm air system from the smaller convertible models but uprated and developed for the E-Class Cabriolet and which is also adjustable for driver and passenger's heights.

The soft top can be opened and closed within 20 seconds up to 25mph and the roof is stowed in a compartment behind the rear panel.

A retractable cover separates the soft top compartment from the boot area and it must be closed in order to close the soft top. If the roof is to remain closed, the cover can be slid rearwards, in which case the boot capacity increases by 90 litres to 390 litres.

A through-loading feature is included as standard for the new Cabriolet, as is easy entry - a manually operated entry and exit aid for the rear passengers.

The powerplants for the new E-Class Cabriolet are equally innovative. The new direct-injection diesel and petrol models combine efficiency with superior power delivery and low emissions.

Good fuel consumption has been achieved through the introduction of new engines, and with a number of practical measures.

These include on-demand activation of the steering and fuel pumps, the use of tyres with low rolling resistance and an alternator control system which takes account of the current driving situation and the vehicle's electrical power requirements, plus the crucial factor of outstanding aerodynamics. The Cabriolet's aerodynamics is the best in its class.

The Cabiolet is available with BlueEfficiency engines as 170bhp 220, 204bhp 250, 231bhp 350 diesels and petrol 184bhp 200, 204bhp 250, 292bhp 350 and 388bhp 500 models. Prices rise from £33,270 to £53,390.

I tested the anticipated best seller in the soft-top series, the E250 CDI BlueEfficiency Sport version at almost £37,500, but equipped with over £8,000 of extras.

Coming from the smaller C-Class you might expect the 2.2-litre engine to be struggling in the bigger 1,815kg Cabriolet but it actually performs very well, delivering immediate, strong and smooth performance.

The £1,500 optional five-speed automatic transmission produces smooth change under hard acceleration and overall I managed to see 39.2mpg achieved, some way short of the maker's figure of 45.6mpg.

The new Aircap system worked very well, being simple to operate and very effective in use with the windows raised and Airscarf working along with the draught-stop.

The hood was very snug when closed and raised and lowered quickly, ideal in the British summer when showers can strike with little warning.

The four-seater cabin was roomier than many 2+2 models and the boot had a reasonably good capacity for shopping or small soft bags.

There is no doubt the Mercedes-Benz E-Class Cabriolet is a brilliantly engineered and roomy soft-top and while its list price is high, the fact it does so much and is comparatively rare should ensure strong residual value as well.