BMW comes up with the coolest convertible yet

BMW comes up with the coolest convertible yet.

BMW has whipped the leather upholstery in its new 3-Series convertible into shape so the seats won't burn your backside in the summer sun.

The luxury carmaker says its "sun-reflective" technology is a world first and allows owners to leave the roof down for prolonged periods in the sun without singeing themselves on the seats or armrests.

It treats the leather in the new hard-top convertible with pigments to reflect infra-red radiation and says it can remain up to 20C cooler than untreated leather.

The new leather is expected to be an optional extra when the four-seater line-up goes on sale in New Zealand next year.

The company has moved away from a folding cloth top for its fourth-generation 3-Series convertible. Instead it uses for the first time a retractable three-piece hard-top, complete with rear and side glass windows that it says improve visibility over the outgoing convertible by 38 per cent.

The roof opens and shuts in 20-odd seconds and is similar in operation to offerings from Mercedes-Benz, Peugeot and Renault.

BMW says that with the roof up the boot in the new model has 350 litres of luggage space. With it down, 210 litres is available. The rear seat backrests can also be folded flat to provide additional storage.

The new 3-Series will be unveiled publicly at the Detroit motor show in January.

The model line-up is expected to be confined to two six-cylinder engine options: a naturally aspirated 162kW/270Nm 2.5-litre unit and the company's new twin-turbocharged 228kW/400Nm 3.5-litre powerplant.

No word on price here yet. BMW in Britain has the 325i convertible down at a starting price of around £33,000 and the 335i at £38,000. That's around $97,000 and $112,000 in our money.