Last fall I did some more insulation and weatherproofing work in the walls and ceiling of my "under the bedrooms" garage (1960s split-level, lousy 2x4-framed construction). I have a 5000W heater on the ceiling running off a 40A Zwave switch, and I've programmed routines to have it keep the garage between 50 and 60°F when it's above 10°F outside (the point below which my electric utility switches to a significantly higher rate per kWh); below 10°F, it only switches on at 40° and warms the garage to just 50°. Since beefing up the walls and ceiling, the garage heater barely ever switches on – once last night (though the low was 0F, and it hasn't been above 15° for a couple of days). Last year under similar conditions, it would cycle on and off every few minutes.
Extreme cold weather wouldn't be an issue if you had a heavily modified 305hp @ 6000RPM tuned 2017 JCW.