Let me tell you something about my maruti zen car, well I brought it second hand 2 months back, I got a good deal on the car. I took the car used it. I took it to mechanic he said the owner had only topped up the gas and made it working but there are still some issues you need to top up the gas and service it to become more efficient .
I will say it is a good car give mileage of 20 on highways and 16 in the city. Only thing you have to service the car time to time change the oil and other lubricants like gear oil coolant etc time to time