Stage 4 - Clean Sweep. Stage 4 features 5 Challenges, all at Dubai International with your Maserati. Each race is a Cup race with a full grid. Nothing too crazy here, and it's a pretty quick stage. As always, if you find you're struggling to win these, either upgrade your car or dumb down your bots. However, whatever you do, don't downgrade your dumbing down.
Challenge 1: 2 laps. You have to take 1st place before starting the 2nd lap.
Challenge 2: 2 laps. Win without sustaining any damage. If you haven't done this type of challenge before, be aware that small bumps generally won't result in the kind of damage that will disqualify you.
Challenge 3: 1 lap. Win the race 310 yards (283 meters) ahead of the 2nd place car.
Challenge 4: 2 laps. Apparently you are running this race with reduced speed and acceleration. To be honest, I did not notice much of a difference, and won with a lead similar to the other races. I'm not sure how you would know what they are doing to your engine.
Challenge 5: 2 laps. Win without going off track.
Completion bonus: $20,000 & 10GC
My approach with all of these is to move to the far right as soon as you start and ride the line past as many cars as you can down that first straight. By the time you get to the first turn, you should have passed many of the cars. To avoid damage, I cut the corner at that turn, and was left with only a few more cars ahead of me to work past.