> * a truck is just a car that misses a roof over the back part of it

Respectfully, a truck is not just a car missing the back part of it. It often has a lot more power, is lifted, has off-road springs, larger wheels, low and high speed gear box, roll cage for the front cabin, raised air intake - the list goes on.

Most people, though, do just need a car with a removable back.

In any case, the "truck" from the article doesn't seem to have all that.