diesel is used for alot of low-end torque vehicles. thats why many pickup trucks use diesel, so that they can get alot of power out of RPM's that would normally stall a gasoline engine.
eg. i've driven a diesel flatbed pickup recently and it would start moving by just taking out the clutch. this was in 4L 2nd (the 4x4 transmission was in 4th gear in low-range, while the main transmission was in 2nd gear) doing about 500rpm. my Ford Focus would stall if I tried to drive it in 2nd gear and at 500rpm.
diesel engines also lubricate the engine. gasoline does not.