Cat & Mouse.
I only played it once (with strangers). Quite different from what I usually do also, but it was hilarious. I wouldn't be surprised if there was a thread here with games like that, but I tried to explain;
Anyway, we played it on the Nurburgring 24h layout and the available cars were set on "Recommended". There are two teams, each team has someone driving a slow car (Daihatsu Copen in our case), all other players have something faster (well preferably); SLS', Gallardo's, etc. doesn't really matter. And yeah, when you pick cars, stick to one color per team.
You start a race with 1 lap, the two Daihatsu get a lead of a minute, all other players wait. Your team wins if your team's Daihatsu crosses the finish line first. So the goal of all other players is to help your Daihatsu (push it), and/or obstruct the other team's Daihatsu or the other team players.
If both Daihatsu's were too far apart we did wait for the other team (would only get boring otherwise).