Most people, especially enthusiasts who love to buy and sell cars, typically aren't aware that there's a limit to doing that. If you're just buying cars, then most state laws won't limit an individual to doing so. In other words, you could buy as many cars as you want within a 12-month period. However, this changes if you, an individual, sell cars quite often. Most state laws say that a private individual could only sell 4 or fewer cars within a 12-month timeframe. More than that, you'll need to get an auto dealer's license from your local state government. This also means that owning these cars, with a dealer's license, requires additional taxation.