Hi Mimi
Second-hand is a term meaning that that the item in question already has previously been sold at retail. We, in the U.S., tend to say a "used" automobile, although in this world of spin and euphemism, such vehicles sometimes are called "pre-owned."
In reality, automobiles called "second-hand" may actually have changed hands multiple times. If it's important to emphasize that Tim is really only the second owner, I would word the sentence somewhat differently.
In the case of the MGF, the model was introduced in 1995 and apparently became the MG TF in 2002 (see
http://www.mgf.ultimatemg.com/group1/info/mgf_history.htm) and as such, "second-hand" or "used" probably is obvious.
These are nuances, of course. Your original sentence is quite understandable.
As a further note that might be of interest, Barbara Streisand, the American singer, had a popular song a while back called "Second-hand Rose" The lyrics are
here.