Have you guys tried dedicated driving shoes with the round heels?
Having a shoe with the typical squared off heel with an "edge" would just intuitively put pressure on a smaller spot on your foot and might be causing your problems. The weight of your foot/leg is resting on the back of your shoe, that then gets focused on your heel by said "edge".
Interesting idea - I haven't tried that. I generally wear running shoes (one of the many "solutions" a doc gave me) that have padded heels, but that could be worth a shot. Thanks for the thought.