A Cybertruck is 224"long x 80" wide, or 124.4 Sqft (Neglecting windshields, I'll mod it with periscope cameras. Besides it drives itself) Probably a little more because of angles, but let's estimate.
125 sq ft is 11.6 sqm. Per Hanks post the sun gives me 1.4Kw per meter, so my CyberTruck Solar gets 16.4 Kw of sun power. It's got a 123 KwH battery, so I only need 7.5 hrs of full sunlight to fully charge it.
I'm not so sure about your calculations, but you're right about your conclusion.
Total daily solar irradiance in Florida is at best 5.5Kwh/meter squared/day.
11.6 square meters * 5.5Kwh * 0.226 efficiency of a lightweight solar panel gets you 14.42Kwh/day of sun power.
Assume 85% charging efficiency and we're down to 12.26Kwh/day actually delivered to the battery.
For a Cybertruck it looks like it gets somewhere around 2 miles per kwh, which would mean 24.5 miles of solar travel per day of full sun.
Realistically, we'll have much less solar panel coverage, but even with 6.65 square meters of coverage we're looking at about 7kwh/day or 14 miles of solar travel. That would, interestingly enough, cover almost exactly one quarter of my regular two-way commute. So instead of recharging every 4 days I could recharge every 5 days.
As long as you park it in the sun, you have good insolation, and don't drive too much, it honestly could make a little bit of difference.