My oldest returned to college a few weeks ago - sophomore year, engineering, full ride.
He came home for the summer and worked at an engineering consulting firm as an intern. They paid him well and loved his work. During his last week, they asked him to stay on the books as an employee and he could telecommute from across the country at his leisure - working as many or few hours a week/month as he wants.
Seems they have an auto enrollment for their 401k, and currently it diverts a mere 2% of his (small) salary to a fidelity account, escalating to 3% in a few months. There is a match but I'm unsure of the details. He is likely to work for them through at least the end of his junior year.
Money does not burn a hole in this kid's pockets. He really hasn't spent any of his summer earnings and since he's on a full ride, he doesn't really need to tap any of it.
I'm pretty sure I could convince him to up his contribution but what is reasonable? DH and I max out our 401k/457 plans but that probably won't work here since kidlet is working but part time-ish. (I'd love to say ALL OF IT but that probably won't fly.)