do you mean the 20 wins a day? You bet money on races, or wait until the next day to farm more cash. Also, don't forget to do the drivers challenge every day.
http://racingrivalsforum.ciegames.com/forum/the-neighborhood/unsupported-player-trades-sales/1194708-turf-cars-for-sale Pick a package. Also have Nismos, rwbs, etc...