I'll occasionally take the wheel of our Yukon XL on family trips when I go home from college (re: Christmas, etc), and my Dad will get ALL OVER me about keeping both hands on the steering wheel, not going more than 1mph over the speed limit, tailgating, checking my mirrors/blindspots before changing lanes to pass on the Interstate... he's a really safe driver, but usually drives with one index finger holding the bottom of the steering wheel at 5-8mph over the limit, no turn signals when changing lanes, etc etc... :disgust:
And don't even think about passing people on two-lane roads when he's riding shotgun! Ugh, yes I know what you're talking about. Drives me nuts.