In my opinion, not having to deal with oil spills and carbon emissions will certainly win out in the long run.
Putting solar panels on a car is a good idea that sounds like a dumb idea that sounds like a good idea.
Solar panels don't actually generate anywhere near enough power to supply a car continuously. (1 horse power is about 700 watts. If it takes 10 HP to maintain highway speeds, that's about 7000 watts, more than most rooftop solar installations.) So, driving forever on a sunny day without stopping isn't something that's attainable except on specially-built cars with tiny motors and giant bodies and don't move at highway speed.
However, if I think about how I use my own car on a typical day, I drive a couple miles to work, park in the sun for about 8 hours, and then drive a couple miles home. Maybe stop on the way for groceries. If I had an electric car with a solar panel generating a hundred watts or so while it sits in the parking lot, that might be enough to keep the battery topped off.
I'd still have to plug in once in awhile if I drive around more than average or if I'm going on a long trip, but if it noticeably reduces the number of times I plug in per year, that's probably worth the added weight and cost.
(I realize that by "solar powered" you probably meant rooftop solar and charging at home or perhaps utility-scale solar.)
(I also realize that I could just ride a bike, but I'm lazy and technological cost-benefit analyses are more fun.)
Has the nice advantages of keeping your car cool in the summer and removing another piece of complexity in your car.
You could also set up the charge stations such that they either draw from the solar panels or from an alternate power source in the winter when there isn't enough sun to keep a really simple solution.
Most cars get really close to 3.3 mi/kWh. So unless your commute is really short, it's not going to make a huge impact on the number of times you need to plug in.
Another way to look at it is if I could get one extra kWh per day from solar and can go 3.3 miles per kWh, that's about 100 extra miles of range per month. I typically drive maybe 200 or 300 miles per month, so that's a pretty big reduction in total plug-in power that I would need. (In our Oregon winters it might not help so much, or if I can't reliably find sunny parking spots.)
Is this assuming the car is parked outside the entire day or just the 8 hour work day?
The petrol industry has many friends, they serve many markets.
Look at what comes out of a barrel of crude[0], an incredible number of products which aren't going away, even if every car/truck/bus/vehicle on the road was electric.
[0]: http://elsegundo.chevron.com/abouttherefinery/whatwedo/whati...
I don't know what portion of that is passenger cars, but it's probably substantial.
1. https://www.eia.gov/energyexplained/index.cfm?page=oil_use