Found a easier and quicker method to XP and money farming.
Big Valley speedway - Outer Oval loop
Automatic, abs - off, traction - off, stability - off
You: Pick the Grand Duke (if you have have it otherwise pick another high strength car)
Ai car: Sofa car
Depending on how fast you are with wrecking the AI you can do this between 5-10 minutes. I am averaging about 6 minutes a race. I am getting 50,796 xp and 7,930 credits.
The point of this is to start wrecking them as fast as you can. For the most part they tend to kill themselves off as the race goes on. I find sitting back and letting a few get ahead and then colliding head on with the lead car, I was able to get 2-3 extra kills on some of the races because there isn’t a lot of maneuverability with the sofa cars. It took me a couple races to get it down but I am already level 28 as of this tip.
Once you are the last survivor you can ram yourself into a few walls until it’s over. Bam, about 50k xp and nearly 8k credits every 5-10 minutes.
There are other great guides but this has been the fastest for me. If you leave a negative please let me know why, this is my first guide! Thanks!