I live in a rural village. There's a bus, which I take in the morning when I get the train somewhere, it doesn't run in the evening though, nor does it go in the right direction to do things like after school clubs.
It would really be helpful to have a second car for those rare occasions, and I can get a second hand Micra with 12 months MOT for under £1k. I'd drive it about 400 miles a year, which would use say 60 litres of petrol a year and cause about 90 tons of CO2, costing about £30 in petrol tax for the pollution it causes. Fair enough.
However I'd have to pay vehicle excise duty of £180 a year, meaning the actual tax per mile is about 50p/mile rather than 8p/mile.
But this is where it gets bad. If I ignore the sunk cost of the car and the VED, the per-mile cost becomes lower than the bus, thus it is far more sensible to drive than take the bus.
In my opinion VED should be rolled into petrol pricing, or just road mileage pricing -- take an odometer reading at the MOT and charge 5p/mile, 10p/mile, 50p/mile, whatever. It's crazy that the tax per mile is an order of magnitude higher for a car used once a week to go 5 miles than a car driven 100 miles a day.