any 'high protein cereal bar' will likely contain plenty of soy protein...not a great choice IMO.
what I'd suggest, is a whey+casein protein powder. its no thicker than chocolate milk, and about 5oz of fluid. Make it with skim milk, and grab some fruit for the drive to work.
I myself have my wife make 5 egg whites and 2 yolks, scrambled, almost every morning. sometimes I drop a yolk and white, and add a little morningstar breakfast "sausage" which is like veggie sausage. its soy and veggie protein...i don't do it often, but its pretty tastey, so it serves to break the monotony.