BMW's new convertible, which is based on the 4-series coupé, features a refined folding metal hardtop and is offered with a range of engines. Prices start from £36,675 for the 420d SE, rising to £39,515 for the 418i SE and £44,970 for the 435i Luxury.
The only diesel model in the range, the 420d, is powered by a turbocharged common-rail 2.0-litre engine producing 181bhp and 280lb ft. BMW quotes 55mpg combined and CO2 emissions of 133g/km. The 420d can go from 0-62mph in 8.2 seconds and has a top speed of 146mph.
Next is the 428i, which is powered by a twin-turbocharged direct-injection 2.0-litre four-cylinder petrol engine developing 241bhp and 258lb ft of torque. It's claimed to average 42mpg and emit 159g/km of CO2. It's faster to 62mph than the 420d, at 6.4 seconds, and has an electronically limited higher top speed of 155mph.
At the very top of the range sits the 435i, powered by a twin-turbocharged 3.0-litre six-cylinder petrol engine producing 302bhp and 295lb ft of torque. It has the same electronically limited 155mph top speed as the 428i, but crucially is the fastest to 62mph - covering the sprint in just 5.6 seconds. It's also the least efficient engine in the range, emitting 190g/km of CO2 and returning 35mpg on a combined cycle.
All engines are available with either a six-speed manual or eight-speed automatic transmission. Regardless of transmission choice, the 4-series features a start/stop system.
The 4-series measures 4638mm long by 1825mm wide, with a height of 1384mm and a wheelbase of 2810mm. The 420d and 428i both have a kerbweight of 1755kg, some 300kg more than the coupé, while the performance-biased 435i weighs in at 1815kg. BMW claims an improved 50:50 weight distribution and "very stiff, precise steering".
Five equipment levels are available, starting with base-spec SE and including Sport, Luxury, Modern and M-Sport trims. Standard equipment on the 4-series cabriolet includes front and rear parking sensors, heated seats, DAB radio, dual-zone air conditioning and cruise control.
The BMW 4-series cabriolet will go on sale in March of next year.
A new M4, based on the Concept M4 coupé shown recently, is also expected to launch mid-2014 for around £60,000.
BMW's new 2-series has also recently been spotted testing, with the coupé expected to replace the current 1-series coupé early next year. A 2-series convertible will follow in 2015.
Read more 2013 LA motor show news.