And then you have to figure, if you took the $ and mass budget of the solar cells, could you just make the battery pack a little bigger/better instead for the same or more gain? Keep in mind the gain would be more reliable. You wouldn't have to depend on sunny days, and sunny parking spaces.
You also have to ask if the $ spent on these solar panels might be better spent on your house, where they will never be in an indoor garage, and maybe cheaper/simpler to install.
Not everyone has a garage, or can practically run a line out to the street. A self-charging car would be a good option for many. The charge this can manage is more than I drive, i’d Be very interested.
It manages more than you can drive in ideal conditions. Sunny day, parked in the sun during the day, for probably a ton of extra cost (they are using very fancy solar cells). That might work for people who have a backup plan in arizona with unshaded parking spots available. Hopefully charging stations at apartments and city centers will continue to proliferate to make electric cars viable for more people.
My normal driving is 100 miles a month, mainly on weekends. Plus, I assume they’ll improve capacity over time. Even if it meant having to go to a public charger once in a while, it would still be a convenience.
You also have to ask if the $ spent on these solar panels might be better spent on your house, where they will never be in an indoor garage, and maybe cheaper/simpler to install.