Buy yes. Trade not so much. They're going to offer really low prices on trades because of the glut of vehicles and falling prices. Private party is likely the best way. Already seeing some of this now. Looking at these 2016 ford explorers with 20,000 miles I'm seeing. Msrp was 42,000 . Trade 23,500 and dealer invoice is 29,000. The trade value is a 45% depreciation in one year! With the spread between trade and dealer invoice at 29%. The dealership consultants tell dealers to maintain a minimum 84% cost to invoice so a 16% spread. Meaning the cost to buy the vehicle, recondition, and keep until it sells should be at a maximum 84% of the asking price. This allows for 12% profit and 4% to the salesman. They're pricing these vehicles at 25-30% above trade and cost, and from what I've seen not budging much. Most of them offer basement prices on trades over 4 years old also.
I saw a cost breakdown yesterday that said cost to recondition and finance runs the dealer about a grand on every used vehicle. 750 on reconditioning and 250 on finance fees. Every month he has it is a month he loses equity because they finance most trade purchases. So they pay 23,500 and it's costs them 24,500 total. I start negotiations there. While that is 0% to the dealership you never know, they could be close to hitting a sales goal, bonus goal, or just need to lower their finance amount and you might end up in the 25-25,500 range which is 2-4% for them. But anything around 27k is good because that's 10% and they used to sell used cars at 10% all day long before the bubble.
You should copy that post to the thread I started about loans...that's some damn good info.