ive taken my smart up the hill a few times already. did highway 38 to barton flats, 30 to green valley and 18 to arrowhead. and each time towing my tent trailer, aprox 500 lbs. i can keep up with traffic and even passed a SLOW vehicle, but were not racing up the hill :-). i dont mind letting the hot rodders pass so i do use the turnouts when available. but i do keep up no problem.