Sales are a great way to get cars for a reduced price, especially the higher-end cars. These sales usually occur almost every single weekend, and start right away Friday, and end sometime Monday. These cars can be up to 50% off, and can vary depending on the vehicle. In addition, sometimes these sales are applied to the In-App Purchases, and can be up to 40% off (They also usually last shorter than the car sales)! The way I try to get cars is to wait until they are on sale, and try to buy them. Even though sales occur on the weekends, occasionally a car may pop up with a token or credit amount for a few days. After a few days, that price/discount can disappear. A car that commonly goes on sale is the HTT Plethore LC 750. I see it almost every weekend (like 80% of the time) on sale for a minimum of 20% off, and a maximum of 30%. These sales don't apply to upgrades, as they remain full price.
Sometimes cars that were only obtainable by winning one of the various large events can be purchased, with a high expense of tokens.