BMW has lifted the lid on its new 4 Series Convertible model due to hit the streets in early spring.

Lower, wider and longer than the 3 Series version it replaces, the newcomer features a three-piece retractable metal hard-top and will cost from £36,675 for a 420d SE variant.

The roof can be raised or lowered in 20 seconds and at speeds of up to 8mph while the optional wind deflector can now be stored behind the seats when not in use.

A new Air Collar system blows warm air around the necks of front seat occupants for open-air driving on cooler days.

From launch the range will comprise two petrol engines and a diesel, available across five different trim levels - SE, Sport, Modern, Luxury and M Sport.

And despite a small price increase, the line-up boasts a marked increase in standard equipment.

BMW says the 4 Series Convertible also has plenty of space in the boot, even when the roof is lowered, with wider access to the 220 litres of storage area.

With the top up the capacity rises to 370 litres - some 20 litres more than in the 3 Series Convertible - and there's an optional through-loading system to open up a level storage area can be used when the backrest of the rear bench seat is folded down.

Heading up the range is the 435i Convertible with its 306bhp straight-six 3.0-litre petrol engine, capable of accelerating from 0-62mph in 5.6 seconds on the way to an electronically limited top speed of 155mph.

Average fuel consumption is from 34.9mpg and CO2 emissions from 190g/km.

The other petrol powered version, the 428i Convertible, has a 2.0-litre four-cylinder turbocharged engine with 245bhp and figures of 0-62 in 6.4 seconds and the same top speed. It can return 41.5mpg with CO2 emissions of 159g/km.

The diesel engine choice at launch is the 420d Convertible, producing 184bhp, 0-62 in 8.2 seconds and a top speed of 146mph. Average fuel consumption stands at 55.4mpg and C02 emissions at 133g/km.

A six-speed manual gearbox is standard but customers can specify an eight-speed automatic offering manual gear changes via paddles on the steering wheel.

Prices are from £36,675 for the BMW 420d SE Convertible, £39,515 for the 428i SE and £44,970 for the 435i Luxury.