Comfort noticeably smooths the ride out, but it has it's limits, it can't work miracles. Sport feels noticeably less harsh than my MK5 GT Sport TDI170 on 17" rubber, not sure whether that's progress in the chassis or the ACC at work. If you want to save whining inlaws then by all means buy it, they'll find something else to moan about personally i'd tell em to get the bus if they'd prefer it or pursuade them to pay for the ACC. I would expect back seat passengers have most to gain from ACC in comfort, not the driver.