Not a medical opinion here but it could be the way you sit. Have you changed your car or the way you position the seat? Also, eating or drinking (especially fizzy drinks) could be causing some discomfort. Just something to consider.

I guess so, tis weird. Probably just anxiety to be honest I guess.

get checked out...could be I.B.S irritable bowel syndrome...
you can get stuff for this...but yes ! RELAX MORE

Trapped wind??? Extremely painful. Is it crampy like pains? There's an advert on the TV for over the counter tablets for this type of stomach pain (Buscopan)

what about when you sit in other situations? interesting it doesn't happen when flying - something to do with angle of seats perhaps? You'd be more upright in a plane seat with a different angle of bend at the waist. And do you keep your fluids up on long car rides or try to do the lot without a stop?

You haven't changed cars have you???

I don't tend to fly I think it's just anxiety, I get a funny tummy on days off Stress I think. We do stop yep.

days off - so not at work?? Do you walk/ stand significantly more/less at work? Is it a filtered water supply there?

nope just tap water...and I walk around most of the time. Filtered water we shall not be so lucky.

so you normally walk around a lot and all's well but when you sit in the car for a long journey the problem happens. It's worth talking to your doctor but I'm wondering whether the change in posture and constriction caused by the bend at the waist is behind this. One test to try the theory might be to go by train for a similar duration but move around a bit during the journey rather than sit still (altough even seated you should have a less constricted posture). If that went well it would start to rule out the anxiety option.

I am the same but it is all forms of travel and any journey length. As a child I suffered badly from travel sickness and it still affects me sometimes. I think it's an anxiety thing connected to that, kind of like IBS but only when travelling. I try not to think about this when I'm travelling anywhere and it certainly doesnt stop me from going on holidays, short trips, weekends away etc. I just accept it now and make sure I enjoy myself before I have to travel home and suffer all over again. Peppermint does help me and I always make sure I have a stash of peppermint sweets of any description on me when travelling, the ones with real peppermint oil in them are the best. I am not a good travel companion but my family are used to that and just leave me to it. I cannot read in a car or bus, just makes me really nauseous. Can only read for a short time on a train before the nausea kicks in but once my stomach has settled after take off I can read on a plane. I have spoken to a number of people over the years who suffer the same symptons so I know it doesn't help but you're not on your own.