MADE to measure luxury for four is how BMW describes its latest 6-Series Convertible, which goes on sale in the spring.

The grand tourer is longer, lower and wider than before and boasts the highest ever level of standard specification on a Six model.

A pair of turbocharged petrol engines, a newly developed chassis plus some fresh driver assistance technology will also feature, along with enhanced interior space and comfort.

A key element of the convertible is its multi-layer roof, which now has improved sound-proofing and insulation, with fins projecting towards the rear to give the 6 Series a more elegant profile than its predecessor.

Opening the soft top - now available in three colours including a new Anthracite Silver effect - takes 19 seconds and is via a button on the centre console, while opening and closing can be completed on the move at speeds of up to 25mph.

Despite its lower height, BMW says that the new 2+2 has greater headroom in both the front and the rear, and height adjustment of the driver and front passenger seats now cover a greater range too.

Two petrol engines - the 650i and 640i - will be available from launch, the 4.4-litre V8 unit in the former producing 407bhp and the capability of sprinting from 0-62mph in 5.0 seconds. Average fuel figure is 26.4mpg with CO emissions of 249g/km.

The 3.0-litre six-cylinder engine in the new 640i Convertible develops a maximum 320bhp and can hit 62mph in 5.7 seconds and on to an electronically limited top speed of 155 mph.

Efficiency is also strong with a fuel return of 35.8mpg on the combined cycle, while CO emissions are at 185g/km, and this model is fitted as standard with an automatic transmission that features a Start-Stop system.

As for technology, features like surround-view, night vision with pedestrian recognition, parking assist, lane change warning and speed limit display are all offered while the convertible is also the only car in its segment to be available with a head-up display.

Standard kit includes 18-inch light alloy wheels (19-inch on the 650i), Dakota leather upholstery, eight-speed Sport auto transmission, electric seat adjustment, BMW Professional Multimedia Navigation system, Xenon headlights, LED front fog lights and front and rear Park Distance Control.

Models go on sale on March 26 and prices will be announced later.