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.
Of note, flexible panels are easy to install but have terrible power output per square meter.
For 8m2 that's 911 kWh. So at an average 2.5 kWh per day.
I guess 6.3 kWh a summer day is not unrealistic.
(I thought your number was way too high but it seems to check out ...)
Assuming say 60% of a 2m * 4m vehicle + some side panels @ 22% efficiency. You might get 6 hours * 220w/m2 * 2 * 4 * 60% = 6.3kWh that’s 25 miles at highway speeds and a fair bit more when your doing the equivalent of hypermiling.
I don’t see anyone trying to overland an EV but people do occasionally mess up and run out of gas on roads in the middle of nowhere.