I've thought about this KERS and grooved tyres issue long and hard. Going from the colour scheme of the player's car, it's a Ferrari F2001 in Monza trim. Well, almost: http://www.f1fanatic.co.uk/wp-content/uploads/2006/10/michaelschumacher_ferrari_monza_20011.jpg
Also, there are green cars on the track. Those are definitely Jaguars (as opposed to Lotus), or you'd have to pass them 3-4 times per race.
This explains everything! :)