I haven't either. I have a feeling they never saw mass production. I would think that it would be a bit unstable.Never seen one of those.
Less if you turned on the heater.Uphill it would do 4 mph. Flat out.
the 'heater' in a beetle is nothing more than a flap in a tube that leads to the exhaust manifold. no other moving parts.Less if you turned on the heater.