I doubt that any natural person will be able to give you a guarantee that at cheap car will allow you to drive for 5000 miles. Most likely the contract can state that individual parts on the car are in a good shape, but even new car dealerships don´t give contractual confirmations that the car will be able to drive without problems for x amount of miles. So my advice would be to rethink this requirement.
 
Regardless of wether or not you want to heed my advice, can you elaborate on the 20 items you are offering in exchange for the car?