Crystal Hefner drives a Smart car.

The Playboy model - married to the magazine's founder Hugh Hefner - drives the modest microcar when she's out and about in Los Angeles, as well as keeping a more luxurious motor for special occasions, although the babe is thinking of trading them in for an eco-car.

Asked what she drives in an Twitter chat, she replied: ''A Smart Car and a Bentley. Hoping to trade them both in for a zero emission Tesla soon!''

Manufacturer Tesla make electric cars which can run up to 245 miles one battery charge and have zero carbon emissions, making them far better for the environment than standard petrol cars.

Crystal, 27, also opened up about whether she and Hugh, 87, will have children, saying: ''That's a great question and I'm not sure if we know the answer yet! Anything is possible!''

The blonde star - who released a track, 'Call the Cops' last year - also said she is looking to further her pop career, and has been having meeting with record executives.

She added: ''Had a music meeting today. Next up will be either a full album or an EP. Looking forward to sharing it with you.''