I don’t get the point to these solar car races the colleges waste their money on. What is the benefit to man? These cars will never please the soccer moms, and improving these tin cans is just an exercise in feutility. I am for applications of solar power, but I see this as a wasted effort. The factual question is…why do they do it? Science & Technology? or, Publicity? - Jinx 
Because forcing people to work for every tiny bit of efficiency for a race tends to create technological improvements that trickle down.
Just like auto racing improves cars, bicycle racing improves bicycles, and the America’s Cup leads to hydrodynamic innovations that make their way onto public sailboats and even large ships, and wind up benefitting all of us.
The best I can see is a solar collector on the hood, roof, and trunk, possibly transparent ones for the windshield and rear glass, and hook them up to a trickle recharger on a battery pack.
The competition is not only to drive creative technological development. That happens undoubtedly, but I would guess that the corporate teams with the bigger budgets drive that. No the greatest benefit is getting a bunch of undergrads engineers organized, designing, building and operating a fragile machine. An actual hand on experience is a priceless, and getting plan to paper is an experience all on its own.
I doubt the general public would be interested in purchasing a concrete canoe, but engineering students make them anyway. Same deal with the solar car. It’s a project. The publicity is just a plus.
The reason they have these contests is to give the students experience, and maybe there is an outside chance that some of their work might have some application to someone somewhere.
I worked with a few groups of 5th through 7th graders on their solar car race project (younger students, smaller solar cars, but same principle) over the past 3 years. Building their solar cars was a great experience for them on so many levels. Sure, no new useful technology was developed for the race, but watching a group of students try to figure out how to get more traction to their rear drive wheels (finally a good use for those pesky AOL CDs) was inspirational to watch. Someday these students will use their experience and be out there designing the 2015 Ford Mustang or maybe a new efficient kind of washing machine or some other useful device- who knows, engineers gotta start somewhere.
People build giant air guns and catapults to hurl a pumpkin.
Not everything needs practical applications. Sometimes, it’s just fun.
I thought GM was a pretty consistant winner in that race???