Help identify ninja movie from the 80s (or older)

I've searched google many times and I haven't been able to find this movie. :(

It is a about a ninja who is a (used?) car salesman. The only line i remember is the ninja saying something along the lines of 'I'm just a used car salesman' . Other than that typical awesome ninja movie!

It's prolly the worst movie of all time, but when I was 8 or 9 years old I remember it being awesome. Hopefully someone can help find this movie.