US carmaker Ford will roll out a feature on 2010 models that can limit teen drivers to 80mph, using a computer chip in the key.

The system, only available in the US, will also give parents the option of programming their childrens’ keys to limit the volume of music and sound continuous alerts if the driver doesn't wear a seatbelt.

Jim Buczkowski, Ford's director of electronic and electrical systems engineering, said: "Our message to parents is, hey, we are providing you some conditions to give your new drivers that may allow you to feel a little more comfortable in giving them the car more often."

The feature, called MyKey, is limited at 80mph even though motorway speed limits are lower in most states because it wanted to leave a margin in case an unusual situation arises, Buczkowski said.

In some states, motorway speed limits are above 70mph.