If your going to be driving then I'd go with a shake. I eat quite frequently in my car and it can be a challenge sometimes, especially when your car is a 5 speed!
i made and ate a tuna salad sandwich on the motorway last summer, i was late, hungry and traffic was bad so drained the tuna, spooned some pickle on some ripped up bread, added some hand shredded peppers and didnt miss a meal!
not recommended though, and if you do make sure you have ring pull cans.
and they worry about mobile phone users!.....