There's one very good reason to consider buying a used vehicle versus a new one: depreciation. A new car will depreciate 10% in the first month it leaves the lot and 20% within its first year. After five years, the average car is worth about 40% of its original price. That might be depressing news for the original owner, but it's a good deal for the prudent used-car buyer. A model that is one to three years old should still have some time under the manufacturer’s warranty. And unless it has been abused, it should be good for many more years of service.That creates buying opportunities for savvy car shoppers who know how to negotiate used car prices.Key TakeawaysDo your online research first to identify the type of car you want and the price range you can expect.Set your maximum price in advance and stick to it.A deal with a private party can save you money, but purchases from dealers are backed by lemon laws.Getting pre-qualified can boost your negotiating power.Certified pre-owned veh...