When I bought the car, there was a hole in the gas tank, which I did know about, but the cost to replace the tank and the gasoline sending unit was about $1000. The sending unit was so rusty that the mechanic could not use it in the new tank.
After about a month of routine driving, the cross-member under the rear end rusted in two and broke as I was driving down the road at 45mph. I nearly lost control of the car. When I got the car to the mechanic, he checked and said that the entire rear end of the car was so rusty that I will have to find a new rear end from another car, as well as have major welding done to repair the rusted cross-member.
The car gets really good gas mileage, about 30mpg, and I like driving it, but now I can't drive it at all, because I have to save the money to do another $1000 in repairs.
It is a well used, ten year old, 110,000 mile budget Korean built four wheel drive-what did you expect?!
My guess is that it has spent time off road and the mud has never been properly cleaned off and so corrosion has set in.
Bad luck; but get the next purchase checked by an engineer-the small outlay would be paid back through initial renegotiation or by not buying a car with expensive faults.