Easy money
Note: This does not work on high priced or third party cars. Buy an old or new junker from the auction. Do not repair this car. Just take and buy a new car door from the catalog. Put the door or whatever part on the car and auction it. This will generally make anywhere from $78 to $1,000 profit.
God-like mode
Do all the jobs you can. After it says that there are no more jobs, get a cheap car from the auction, fix it up, and try to get more than $20,000, which will get you to God-like mode.