Swamp Molly - S1-E6
Revealing mistake: When the truck goes into the water, you can see the driver was either a stunt driver or a dummy. Also, you can see the top of the truck just under the surface of the water, suggesting it was on the bottom. A few seconds later, and all you can see are bubbles.
Answer: Various reasons, but mainly to drive the Dukes out of Hazzard County because the family have been foiling his schemes since his and Uncle Jesse's bootlegging days.
Captain Defenestrator