old sube hauling a complete engine
there are many reasons for a truck.
weight limit of car execeeded
density of item hauled is greater than the unibody metal (number one worldwide error- that is NOT a big bad 4cyl wagon you got there)
the above photo is an ode to welding, over 5 reels of mig, about 75 pounds of steel, and finding oem anomolies. I learned the 3 main is the "heavy hauler" for the four banger world and gave it a body with alot of work mind you. this one hauls its own engine, without a pallet, oil pan being the point of all the weight. I expected a squish in the body, and there wasn't. I joke of it being a half ton sube. do not try with a normal car. Also, if to haul with a trailer hitch, you may find your car has a class two hitch version and a class 1 receiver, go for that one, do NOT use the class1 and class1 receiver together, it is a ripoff.
other than that, a truck creaking and moaning down the road could be your best bet, let the car creak and moan to its own weight limit, One needs to learn many specifics. If you are a transverse drivetrain, stay close to oem limits, (and it aint much).