1987 Mustang GT. Would take whatever I threw at it, including my foot up its [censored] most of the time, and the engine is STILL going with 300,000Km on it now.
Close runner up is my old '97 Explorer, now owned by my sister. Another vehicle that would just TAKE the abuse and reliable as death. It has never left either of us stranded; it has never needed as much as a boost, let alone a tow truck. Currently has 307,000Km on it.