It depends whether you consider the whole cost of running the car. Some time ago I kept a nauseatingly comprehensive spreadsheet on all of the costs of car ownershop over 4 years and 170,000 miles.
The car in question was bought second hand and the mileage was large (so depeciation was understated) but the cost of running a Mercedes C200 turned out to be 28p a mile, of which fuel was a little over 12p a mile.
On the other hand, the depreciation on a Fiat Coupe over 10 years and 40,000 miles was over 50p a mile, so it cost somewhere between 65 and 70p a mile to run.
Using a figure of 50p a mile (a reasonable cost of running a newish family car including depreciation), the cost of a round trip to London from Bristol is about £130 (plus parking). By train at peak time is well over £150. Off peak it can be as low as £24
Of course taking more than one person in the car only increases the cost by a tiny incremental amount. It's a direct multiplier on the train.
The scary thing is that the ticket cost only represents 50% of the total income, the rest is subsidy. So the true cost should be £300
It seems to me like running a railway is a bit like running an opera house. The tickets are incredibly expensive, it's always sold out, the staff (performers) are paid a pittance and yet, somehow, they still can't make ends meet.
I realise that the train operating companies, train leasing companies, various rail maintenance companies and so forth are all making good money but it still seems incredible that it costs more to take 19th century technology to London from Bristol than it does to take 20th century technology to Rome.
Christian Wolmar has written some interesting books and articles on the railways.
