Thanks to all for your answers and sorry for being out of topic.
>Then there is the problem that combining anti-matter and
>matter produces a lot of radiation, so we would need to
>redesign your car so that you have a big lead shield
>between you and the antimatter engine. At that point
>the car weighs a lot more and you need even more
>anti-matter fuel to make it go.
>Hope that explains it.