Road Trip Calculator Update

Some time ago I created the road trip calculator and wrote a post that went over the calculation of the true cost of driving from Boston to New York City in a $25,000 car.

Today I am making a small update to the calculator. Aaditya Prakash, a good friend of mine who is pursing his PhD in Computer Science at Brandeis pointed out a small flaw in the calculation. Aaditya reminded me that owning a car has a fixed cost and taking a road trip has no impact on that cost. Therefore in order for you to know how much your road trip is costing you, and I mean the road trip alone, then the pro-rated ownership cost needs to be subtracted from the calculator’s result.

Car Ownership Costs #

In order to really focus on the fixed ownership costs – meaning costs that don’t vary based on your driving – let us assume you’re not driving your car at all. What do you need to pay for?

• Insurance
• Excise tax – if your city/state requires it
• Parking rental – if you don’t own your parking spot
• Annual inspection – if your state requires it

So I added an ownership cost section to the calculator:

The annual inspection cost has been omitted because its pro-rated value on a road-trip would be so small it is negligible.

Boston to New York City #

In my original article I took a $25,000 car as an example. I’m assuming $150/mo in insurance and that the parking spot is owned. In Massachusetts the typical excise tax is 2.5% of the car’s assessed value so in our case that would come down to $625 (if the car were assessed the same dollar amount as what we paid for, which usually isn’t the case though). The calculator will also always assume an average of 55mph for road trips.

Result #

The new result is as follows:

$0.3 / mile in car depreciation +
$0.02 / mile in tire depreciation +
$0.09 / mile in gas +
$0.006 / mile in oil +
$0.027 / mile in brake depreciation +
= $0.443 / mile total 

$0.443 x 215 miles + 
$5.54 in tolls + 
$0 in parking 
= $100.8 one way 

$0.2083 insurance / hour +
$0 home parking / hour +
$0.0713 excise tax / hour
= $0.2797 total fixed cost / hour 

3.91 hours of driving (at 55mph) 
3.91 hours x $0.2797 = $1.09
$100.8 - $1.09 = 99.71

Total Cost #

The one-way trip is $99.71 and the return is $199.41. (fuel prices went down since my original article).