Search City car up to 500€

Hello, I am looking for a car, which should be used mainly in urban traffic. My price limit is 500€. Whether automatic or not, I don’t care. It’s important that the car is as cheap as possible in maintenance and consumption. Besides, the car should not be too old. I don’t need a large trunk and a 2-seater is enough for me completely. I don’t care about the interior equipment. Great would be air conditioning. I had thought about buying a smart, but it got me What can you recommend to me as a used car? What do I have to pay attention to with the respective model, how much can he have run and so on? Thanks already