Specifically in the upper thigh. After an hour of driving, the pain starts to kill me. Keeping it bent or stretched out with the foot on the dash only helps a teeny bit. Sitting cross-legged helps more, but of course that’s crazy and dangerous!
The question is why. Why does my left thigh cramp up so bad? Is it because it’s inactive? If that’s the case, why doesn’t it hurt when I’m driving my desk all day at work? It only hurts when I’m driving. And it ALWAYS happens when I’m driving.
And sometimes you can not avoid needing to do the drive =)
I make it work by stopping every 2 hours and gimping around the car once, and every 4 hours stopping to pee and get another bottle of water. When the car needs diesel, I get chow. I regularly do 16 hour drives that way.
Make sure that the side of your knee, or some other part of your leg, isn’t pressed up against the window winder or other part of the door for extended periods.
It could also be something as simple as the position (and adjustability) of the driver’s seat. My wife owns a Toyota Camry and I cannot get the driver’s seat to adjust to a comfortable position for me no matter how hard I try. Long road trips are a killer for me - I get the same pain in my left leg after a few hours that the OP describes. (Of course, that’s the side I keep my wallet on too. ;)) On the other hand I could drive my Hyundai Santa Fe all day and not feel any ill effects, probably because I am sitting more upright and elevated.