 When buying a used car, or any car, 
some people get good ones some get 
bad.  I know several people who are 
happy with their mustang (v6) and don't 
have any problems.  I however had 
problems.  The exhaust manifolds went 
bad twice, but were covered under 
warranty.  After the warranty expired, 
at about 45,000 miles the transmission 
started slipping when you tried to 
accelerate hard, and the valves started 
to make noise.  The dealership told me 
that the valve problem is common with 
the V6.  It cost around $500 to fix.  
The top did make some noise around 
48,000 miles but it was an easy fix.