I do! (safely, at lights etc)
Can't use my right foot b/c of the gas/brake pedal for the bass drum, so I sort of use my right hand as a combined bass drum/hi-hat.
Have an automatic for a daily driver, which helps.
I have found that I am better at "car drumming" left-handed so to speak. I guess all of those years of jumping on my left-handed drummer's drum's when he got up to grab a beer etc must have gotten to me. ;)
It's actually inhibited my progress since I found my Ludwig kit because I think my brain is slightly wired to drum lefty.
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anyway, anyone else practice drums in the car?