That must have looked tiny on your RV. I know people with a 3kw system (edit: 2940W ignoring losses) on a 28’ RV and they had an AC unit blocking some space. Now they don’t actually see that much power because the roof is a flat surface, but it’s enough he never carried through installing solar on the side panels like the initial plan was.
Of note, flexible panels are easy to install but have terrible power output per square meter.
It is my estimate of what will fit on a passenger car. I could only squeeze 410W on the roof of a 26’ RV. I doubt your 450W panel is going to fit even on something like a Land Cruiser.
And “side panels”? Ignoring the impracticality and inefficiency, no one with taste will be driving that. :-)
Besides, if you run out of juice, and if AAA will come get me in the Yukon 180 miles from Whitehorse (flat tire on the bike I couldn't fix), meaning 180 miles from anywhere, then they'll come charge your car anywhere in Wyoming. A AAA card is lot cheaper and more practical silly solar panels.