As part of my used car saga, I continue to find suspicious things with my car. My 05 Mustang GT was purchased from CarMax with 65K miles on it. The CarFax report gave me no information beyond the car was purchased by a private owner. No inspections, no licence plate renewals.... nothing. The first odd thing I noticed on the car was new struts. Why? Then I noticed how clean the engine was. I mean the engine was spotless, with the exception of the dust build up around the spark plug holes. I changed the engine oil and filter. It was very clean. I changed the air filter. It was discustingly dirty. So I went further up the air path and found the throttle body was spotless. No oil, no tarnish.... perfectly clean. The intake manifold also looks spotless. Front timing cover, spotless. Oil pan, clean with normal road dust and dirt. So how can I tell if this engine is new, rebuilt, or what? Any suggestions?