The cool idea (image) is the work of UK science firm Qinetiq, and can also detect if you are sitting close to the wheel. It will be used in the US where new laws require cars to detect the driver's position for safer airbag use.
Tell us about your car in our Driver Power survey.
For more breaking car news and reviews, subscribe to Auto Express magazine. We'll give you 6 issues for £1 and a free gift!