Chevrolet has become the first carmaker to offer an unlimited data plan with its cars.

The deal, for a 4G LTE data plan, applies to cars sold in the US from 3 March and will cost $20 (£16) a month.

It is being offered with the help of US carrier OnStar and will see vehicles fitted with a wi-fi hotspot that connects to the web via LTE.

Chevrolet said it was offering the deal because in-car data use had grown so fast.

Figures gathered by Chevrolet suggest the amount of data used via wi-fi in its cars jumped by 200% last year.

In 2016, it said, Chevrolet in-car hotspots had handled about four million gigabytes of data.

The LTE-based hotspots are available across the entire range of vehicles made by Chevrolet.

The system allows owners to connect up to seven devices at a time.

Ford also announced this week that it had signed a deal with Vodafone to put 4G modems in its cars.

It has not yet released any information about prices but said the system would be an optional extra available in cars sold across Europe from 2018.

In its announcement, Ford said the 4G hotspots would use wi-fi so passengers could connect directly rather than by using Bluetooth.

Car owners will be able to use up to 10 devices in a car at any one time.