[Jack21]

Installed heater/defroster in mine from the start, but intended driving car in all but snow & ice.

If floorpan, firewall, and footboxes are properly insulated, there is no engine heat in cockpit. Heater is darn nice even on chilly summer nights. This was not a futile idea.

With just tonneau cover, car is driven on very chilly early spring/late fall days & nights. Footwells stay toasty.

With top and sidecurtains, car is driven in sub-freezing temps. Car stays right toasty.

Water still gets in during a downpour, but stays reasonably dry in light rain.

Thought rain would enter hoodscoop and wet ignition or soak aircleaner. It doesen't. Engine heat keeps things dry.

Sub-freezing temps will cause plastic sidecurtain or rear window to crack if folded too sharply.

Continue thread and I'll detail how.