Rustad started his motor sport career in karting before racing in the Norwegian Rallycross Championship, winning the so-called Supernasjonal title for six years in a row between 1987 and 1992.

On 14 June 1992 he claimed overall victory in the Irish round of the European Rallycross Championship at Mondello Park, racing one of the two 650bhp strong Ford RS200 Group B cars of his compatriot and mentor Martin Schanche.

After this he spent a couple of seasons racing in the European Touring Car Championship, before returning to Sweden in 2003 in an Opel Astra.

Rustad became the first Norwegian to drive in the World Touring Car Championship when his Polestar Racing team entered rounds 15 and 16 of the 2009 season at Brands Hatch.

For 2015 he was entrusted by his sponsor with a competitive VW Polo Mk5 SuperCar of the Volkswagen Team Marklund Motorsport, which he used successfully to claim his first European Rallycross title.

Of the five rounds counting towards the EuroRX series Rustad won three, beating his strongest competitor Jérôme Grosset-Janin from France to second place.