At home we have an small tractor with an 40hp engine. at one time we towed some logs, at the same time we helped and car to get out of the mud. We just connected the car to the logs.
Incredible what those small tractor engines can handle!
It´s most the traction. On any surface accept conctrete or paved road a small tractor win pulloff against any car. The most funny pulls I´ve seen is a John Deere 8530 ( about 300 hp) against a 6x6 IVECO truck ( 4-450 hp) The tuck didn+t stad a single chans, and was towed backwards at high speed... We have a couple of tractors from our beloved Ford 4000 ( 1969 ) to the newest Valtra N 111 from 2012.
Our Case tractor managed to tear an 2 inch mooringline in two pieces when pulling down a pine. Thats not supposed to happen....