Rod McInnis wrote:

the old Volkswagon Beetles used a heat exchanger off the exhaust manifolds
to heat the car! It was actually pretty nice on cold mornings, as the
heater worked almost instantly after starting the car.

Woah! I had one of those Beetles way back then. It leaked CO so bad it nearly
killed me. I would worry about any heating system that utilizes a heat
exchanger off the exhaust manifolds.

Larry Weiss
"...Ever After!"
"a little after..."