Yes, I find driving with my N-Frame in the PMK plenty comfortable, with some exceptions (mentioned below). In general, I find OWB more comfortable than IWB when driving. I suppose the gun is a little less apt to dig into your ribs, and thus is more comfy. The butt is also a little more free to rotate away from the seatback, increasing comfort.
If you carry as far back as 4 or more, then no, I don't find that carry comfortable in a car. It's like a brick in your back
This is also highly dependent on your seats. In my wife's Toyota SUV, it's very comfy. In my Subaru STI, with much more confining seats, no it isn't that comfortable. But, in that car, even pocket carry is uncomfortable because of the high thigh bolsters. If I'm driving distance in the STI (not usually my choice, I'll take the Toyota), I will wear loose pants so I can kinda rotate the pocket on top of my leg and away from the bolster. It's awfully hard to get into your pocket when seated, though, so if you drive a lot perhaps other options are better--not really for comfort, but accessibility.
In general, OWB @ 3:15 is quite comfortable when driving, although only if the seat is wide enough to accomodate it.
BTW: you can make
IWB more comfortable by buying 33's. The extra inch will be filled by the gun, and you won't look silly at all.
If you CZ's hammer is digging into your skin, you need a holster which incorporates a "sweat shield" (as its usually called), simply it continues up and covers the area between the slide and your skin. This will make IWB
far more comfortable for you. I really like Milt Sparks VersaMax 2's for this reason (among others). There are other brands/makers with similar styles.
I hope that helps.