@ forgotmyoldpassword:
As I said above, it depends greatly on what assumptions you make, and I’ve lost the details in the decade or more since I did it. I haven’t run a car or done much walking for over 10 years, so I don’t have any recent data to repeat the exercise with. Whether you’re talking about utility travel or leisure travel is relevant because it affects whether you calculate per mile or per hour. That makes a large difference because of the difference in speeds, but my calculation was on a per mile basis.
I’ve a feeling that I was getting about 1000 miles out of a pair of Brashers costing about £70 at the time, but there’s a lot more to the cost of walking than just boots. If you’re walking, you need to include the wear and tear on all your other clothing, and the cost of additional food is about 10p/mile (at today’s prices). People complain that motor transport is expensive, but the cost of travelling 100 miles by car is a fraction of the cost of a week’s food and accommodation (and possibly a week’s lost earnings, too). The cost of maintaining my bike has been an average of 3.6p/mile which offsets a lot of the saving on food.
When it comes to the car, it depends whether we’re talking about giving up the car altogether, in which case you save the fixed costs like insurance and tax, or whether you’re just costing on the basis that the car is left in the drive, in which case you only save the marginal costs of the additional mileage. With the cost of servicing, you need to separate the fixed and variable costs, but that depends on how many miles you do. Most cars have a service schedule which says something along the lines of “every 12,000 miles or 12 months”, in which case if you’re already doing less than 12,000 miles/year cutting the mileage only saves wear and tear, not routine servicing costs.
@ Callmesteven:
The benefits of moderate exercise are substantial and well documented, but I think that most people who enjoy an active hobby are going to be doing quantities far in excess of that required for optimum health (like I did, to my cost).