I currently drive 2013 Subaru Impreza hatchback, which seats 5 people (1 driver, 3 comfortable passengers and 1 unfortunate passenger on the middle seat in the back row). Its towing rating in Canada is 0 pounds (I believe this model is rated to tow in Europe and Australia (and maybe elsewhere too, I don't have an exhaustive list) but not in North-America). Despite its tow rating, I would like to be able to tow a small trailer to carry a motorcycle. Let's assume the trailer and motorcycle have a combined weight of 500 pounds. I have seen other people do it, but I still have concerns over damaging the vehicle by putting too much strain on it and creating a dangerous situation.
I did a trip with 4 adult male passengers without issues, so if I replace passengers with a trailer of equivalent weight, are there obvious problems I should foresee? I can I reasonably assume it would be fine?
My question is: in terms of strain/wear on different components of the car and performance (acceleration, braking distance) what's the difference between towing a 500 pound trailer and carrying 4 passengers of 125 pounds each?