6. Choosing a car that's ill-suited to your needs. Before you visit a dealership, consider the type of car that would fit your lifestyle and needs. Do you commute long distances and need a fuel-efficient vehicle? Do you need a large trunk for carting around sports equipment or musical instruments? "A lot of people don't talk about [buying the wrong car] very much," Nerad says, "but it's a big mistake if you buy a car that doesn't suit your lifestyle or a car where there is a logical substitute that would be a better choice." Don't let a flashy car advertisement, car-loving friends or a smooth-talking salesperson steer you away from these priorities.