I mean, the math isn’t hard. 200W out of a panel (at best), multiple by 5 hours to get a kilowatt hour. How many of those do you need to get back to civilization? Our Leaf gets 4 miles per kWh. The hypothetical desert overland vehicle probably gets half that.
You’re better off bring extra water and walking back for help if it comes to it.
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.
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 ...)
The main use case for this would be something like driving an EV across a desert or some backcountry well outside civilization I guess, otherwise it's probably easier to just find an electric socket somewhere.