I just tried the Dodge Challenger Event and got my ass handed to me. So here's a guide on how to cheat and win, to get your ~750,000 credits and ~60,000 EXP in 10 minutes.
If you don't want to cheat, don't read the following. If you want to get the cash and credits, and move on to something you enjoy more in game, then here you go.
I bought the Challenger new from the Dodge Dealership. (75,000)
You don't need to tune anything, other than the Fully Customizable Racing Transmission. (20,000)
Total: 95,000
In settings, change the top speed to 149,155 or 162. I used 155, you'll hit the limiter down the stretch about 1/8th mile before slowing for the corner, but a small sacrifice for a bit more acceleration through the rest of the tracks tight corners.
The shortcuts.
There's 2, and only 1 is really needed to win, the other one, is one I accidentally found when I overdrove a corner.
The important shortcut is on the very first corner after the long straight. Start braking at the same point the 'preferred line' indicates. Instead of following the track, cut to the right, inbetween the tires and the cement wall. It cuts 2 tight corners of the track, and is enough of a shortcut on it's own, to put you right behind the leader as you finish lap 4. Giving you the entire final lap, to make the pass and maintain the lead.
Note that you do not have to fly through this shortcut, slow and steady to ensure you don't spin out. You shouldn't have to go any faster than you would have through the corners. Give it a few tests on the first lap, find a comfort zone for you and make it work. Usually around 55-65mph is the sweet spot for me. Using this shortcut, gave me lap times of mid 1:47's, for reference. I'm not a super driver (obviously or I wouldn't need the damn short cut!)
The second short cut, I only used when I made a mistake. On the very last 2 tight corners of the infield, you can again cut them both out of the equation, by a detour through the grass. This one requires a lower speed, as it's less of a straight shot from the grass and the pavement which can cause a spin.
If you're a worse driver than me, and the above isn't enough, you can do the 450 credit air filter, to max your HP at 425, and add whatever suspension you prefer to help get the car around the track! =)
*Disclaimer
Cheating is bad, I don't promote using short cuts, wear your seat belt at all times, don't do drugs, stay in school and all that stuff.