Using car exhaust for engine Pre- heat??

Typical exhaust gas temps at the tail pipe would not be hot enough. I
would worry about corrosive gases, condensation etc getting into and
behind the instrument panel and gauges. I use the "Red Dragon" and
preheat for at least 30 minutes. Even if you rev'd the engine on your
car, you would never come close to the temps that a good propane heater
does.

Just my 2 cents... Good luck

Terry N6401F