App makes your car sound like a Ferrari

This could be the best thing we've found to keep kids entertained in the car -- it's certainly been keeping the Carguide adults amused.

Vroom: The Car App uses your phone to add the sound of a Ferrari, muscle car, tank or even tractor to your driving. Or just to your walk to the shops.

The app has been developed by RJDJ, who were also behind the Inception and Dark Knight Rises apps. The designers say Vroom uses your phone's accelerometer and GPS to track when you're speeding up, braking and cornering -- and delivers the matching soundtrack. Stamp the accelerator and the engine roars. Corner quickly or slam on the brakes and the tyres squeal in unison.

Free for Android phones but a mere dollar for iPhones, this is some of the cheapest fun you can have in your car. And it works outside the car too, with the phone able to add great sound effects even on a stroll down the street, with a couple of quick cornering manoeuvres to duck into nearby shops.

You get the muscle car free, and can add an extra car -- an excellent imitation of the Knight Rider KITT -- for signing up to the app. Beyond that, an Italian supercar (guess which one) is $1.99, a Russian tank is $2.99, although we have no idea why people would pay more for a tank than a Ferrari. And an Austrian tractor, or horsepower of the four-legged kind are also available.

We're hoping RJDJ keeps adding more vehicles and perhaps even other strange modes of transport, making this the perfect companion to keep the back seat happy on holiday road trips. Thomas the tank engine, Lightning McQueen, the Batmobile, Transformers, trucks, planes, speedboats  ... there's no limit to the fun we could have with this.

This reporter is on Twitter: @KarlaPincott