I think I will go against the grain when I give my sugestion but here it is:
Do not get your doughter a diesel. Diesel fuel is sometimes a P.I.T.A to find, and even under the best circumstances is rare at least here in California. There have been times when I was returning home late and had to take strange detours to get some fuel. This is definetly not something you want your teenager doing late at night!
Any increase in safety you get from a slower car would be offset by that. Also diesel pumps are usually covered in diesel fuel since the diesel does not evaporate as easily as gas. Do you honestly want to deal with having the responsibility of messing up your doughters wardrobe???
My sugestion would be to get your doughter a gas engined 190E. If you are concerened with speed then get a 2.3 liter automatic. Above all: let her choose the color of the car.