Is a 150cc scooter safe on the freeway?

no i dont think you should risk it man. mainly because of the speeds the cars around you will be going. if it was a slow car or something id say maybe, but you dont want to risk being run down by a bad driver just to save some gas. so i strongly recommend you dont. but if you have faith in your vehicle then by all means. why not just get a motorcycle??? 600cc or something, theyre pretty cheap and pretty nice, and will DEFINITELY have no problem on the freeway