31.   But as soon as the driver gives it extra gas, electronic sensors take over and feed power to the rear wheels.

32.   But the driver also has the option of putting the system into two-wheel-drive mode, which operates the rear wheels only.

33.   Car engines that drive the rear wheels sit under the front hood because horses pulled carts from the front.

34.   Computer control is necessary because the rear wheels turn in the opposite direction from the front wheels at low speeds for easy maneuvering into parking places and such.

35.   Do move your butt out over your back tire during steep descents to keep the rear wheel planted firmly on the ground.

36.   Even with electronic stability off, it does its own braking when a rear wheel starts to slip.

37.   Finally, when it was down to a crawl, the driver jumped out and threw a log in front of the rear wheels, stopping the vehicle.

38.   Expeditions with Control Trac four-wheel drive normally operate in all-heel drive, with the rear wheels getting the power unless they slip.

39.   Further, a button on the dash lets you lock half the torque to the rear wheels for slow, heavy headway in the roughest conditions.

40.   Front wheels on the incline, trailer hitch in the road, rear wheels off the ground, back end blocking a lane and a half of Sundance traffic.