Coming down hard on the car driver is never going to work. The carrot and stick approach is the way forward.
I've mention this loads of times before but I'd rather run a car then pay 68 quid a month on the "appt" for unlimited travel. It seems like a good deal at just over £2.50 per day but its no good if the bus your hoping to travel on doesn't turn up. Make buses more reliable, and ALOT cheaper than my car and this will cancel out the negatives i've got about getting bus to work ( noisy passengers, dirty buses, waiting around for a connection etc etc)