Avoid most cars out of a used dealer lot. They’re either overpriced in comparison to a private party or not well taken care of. Their end goal is to transact for a profit, not help you get into a decent vehicle. Lemon law applies to new(er) cars, not old ones (2013 and up in California as of writing). Also, always take an OBD II scanner to check for codes.
Avoid salvaged vehicles you know nothing about repairing. If you have experience, chances are you aren’t looking through this list for help, anyway. They can be a far bigger headache than you’re expecting.
Avoid the car if the owner’s name according to his driver’s license does not match the registered owner’s name on the title. A number of things could be happening at this point, maybe fraudulent identification, maybe stolen car.
Avoid the first year of any generation of a vehicle. For example, the 2004 Prius is infamous for head gasket issues, 2005–2009 are fine. 2010 Prius is infamous for problems with the coolant pump. The 2011–2015 are fine. 2016 Prius had issues with the axle on one side (usually driver side). All other models are fine.
Avoid cars that have had too many owners. When purchasing a vehicle, go over the Carfax or Autocheck yourself. Ask for the VIN. See how many owners it has had and how frequently it changes. Ask questions. If story does not add up, avoid it.
Avoid any car with mysterious gaps in the Carfax for servicing. If there are prolonged periods of time between service, it doesn’t necessarily mean that the car has had an odometer rollback or gone unserviced, but it would always be wise to ask questions as to why. Sure, some people self-service for the life of the car, but, generally speaking, it’s highly unusual to have large gaps in the vehicle records.
Avoid any car with an owner that won’t let you scan the car with your own OBD II reader. Often times, owners can reset the car’s engine light before a sale. Some diagnostic readers will catch codes regardless. Make sure you always have a quality reader when seriously considering a purchase.
Avoid any owner that places the obligation of smogging the car on you. Cars need to be smogged before they are sold, at least in California. This is done by the seller. If this is happening, the person most likely knows something is wrong with the car before they sell it to you. They know it can’t pass smog, so they are trying to sell you the car first and leave the burden to you.
Sometimes private parties will cut off part of the ECU that lets the driver know about issues (ABS lights, Engine lights, etc). If you notice your OBD II is not functioning correctly, it’s usually because they are hiding something. Avoid this and avoid people like this.
Avoid most used cars with massive depreciation. If you look at a BMW M series from around 5–7 years ago, you’ll find them at $30,000 or below. This is the same with Maserati, and the same with companies like Range Rover. It’s because these cars do not hold up to years of abuse and mid-range mileage. The problems really begin out of warranty. I recently rented a Range Rover for a two day road trip, and, within an hour of renting, realized that the car had nearly no coolant. It had 20,000 miles and it was basically brand new. There is a great reason they are so cheap so quickly. Unless you know about the repairs and the issues yourself, stay away.
Avoid any car with panels changed or frame bent. Especially if it has a clean title. This car has major damage, and deserves a salvage title that the owner is trying to pass off as clean. Check the gaps of the car along the panels. Make sure it is all even and flush.
Look for original paint. If it looks like things are replaced with off-looking paint or non-original paint, the car has had some damage or been hit. People will hide accidents for the sake of maintaining a clean title sometimes. Again, this doesn’t mean minor dings and dents. Used cars will have these, and it is important to distinguish the cosmetic from mechanical and structural soundness.
Avoid anyone who is dropping the price of the car drastically for you without any reason. If the car is selling well-below market value, and it seems too good to be true, it usually is. An owner who keeps good care of their car is usually proud of it and understands the value of something well-maintained.
Avoid used car owners that are trying to transact over PayPal or Moneygram or a wire of some kind. This should be a no-brainer, but, just in case, don’t do this. Ever.
I’m sure there are quite a few more I have learned over the years. I’ll add them as they come to mind. As you can see, the usual suspects are not listed. High mileage doesn’t have to be a concern always. I have a 2007 Prius with nearly 300,000 miles and it has had nothing except for routine maintenance. The battery capacity is still at 95%. Other, less obvious things are usually what used car sellers try to get away with.
The employment of good judgment comes from mistakes and experience. Some of those lessons came from errors and others came from things I noticed and avoided.
Used car shopping can be extremely rewarding, both, in the process of learning about negotiation, and in the savings that come with a pre-owned car. With that said, never let your emotions get in the way of a potentially risky purchase. Used car shopping never needs to be scary, and it certainly never needs to be rushed.