Buying a used car is always a risk, even if you get it from a dealer and even if it seems clean and well-maintained. You may know to check the condition of belts and hoses and the tires, and also check the mileage, but may not know what else to check when it comes to ensuring you're getting a good deal. Consider a few seemingly small features to remember when buying a used car so you don't face any surprises down the road.
Checking the tread on the tires will tell you if you'll need to buy new tires sometime soon, but tire tread can also tell you quite a bit more about the car and needed repairs. If the tire tread is unevenly worn in the same spot on two matching tires, meaning the two in front or back, this often means the car needs an alignment and balancing. If just one tire has severe tread wear on one side, this usually signals a bent rim. You may need to get these repairs done soon after buying the car, so you can better control it when on the road.
A car shouldn't have foul odours when running, and these smells can often tell you about needed repairs. If you notice something that smells sweet coming from under the hood, this usually means there is a coolant leak, as coolant has a distinctly sweet smell. If there is a foul, "gym sock" odour coming from the vents, the air conditioner may be holding mould and mildew, and this can cause severe damage if it's not cleaned. A burning smell may indicate a leak of oil or transmission fluid; in a manual transmission, it might also mean that the clutch is burning up and will soon need repair. Have these items checked if you notice any of these smells so you know their condition before committing to buying the car.
Any smoke from under the hood should be investigated, as it can mean the engine is running too hot and needs a new thermostat or fan. The coolant pump may also need replacing, or an oil leak can mean oil is dripping onto the hot manifold and smoking. Smoke from under the wheel well often means the brakes are locking up and not releasing, and the car may need new brake callipers, pads, or rotors. Don't ignore even a slight bit of smoke from under the hood as these conditions can all be very serious if left unchecked.