Is driving now cheaper than Metro? No.

Yesterday, Washingtonian Capital Comment blog calculated whether it is cheaper to drive into DC from the suburbs instead of riding Metro after the fare hike went into effect.

Rodger Nayak found driving to be cheaper “every time, … particularly if you take your car to the subway station and pay to park in a Metro garage or lot.

However, as many commenters almost immediately noticed, his analysis was flawed for several reasons. First, he calculated round-trip Metro cost, but only one-way driving. If you double the number of miles, driving already becomes more expensive in several of the examples.

More importantly, Nayak only calculated the cost of gas and parking, but the marginal cost of driving a mile includes more than that, like depreciation and wear and tear which forces more frequent maintenance and replacing the car sooner. There are also fixed costs, like insurance, but even if we assume that a specific rider already has a car and insurance (which should vary more by miles driven but doesn’t), there is plenty missing.

To their credit, Washingtonian retracted the piece. We’ve gone ahead and redone their calculations for the four examples Nayak picked:

Origin station	Vienna	Frc./Spg.	Shady Gr.	New Carr.
Metro before fare hike (Nayak)	$13.20	$13.30	$13.95	$11.25
Metro after fare hike (Nayak)	$14.40	$14.50	$14.75	$12.15
Metro with “peak of the peak”	$14.80	$14.90	$15.15	$12.55
One-way mileage (Nayak)	16	14.2	22.3	10
Nayak driving cost	$11.92	$11.92	$13.01	$11.35
Nayak 2-way driving cost	$13.84	$13.84	$16.02	$12.70
Using IRS rate for total ownership cost	$26.00	$24.20	$32.30	$20.00

All trips involve commutes from the listed station to Metro Center. All assume a commuter who parks at the station (it’s cheaper to take the bus to the station or live near a walkable station).

Nayak doesn’t factor in the proposed “peak of the peak” 20¢ Metro fare. The third row above assumes a rider commutes both ways during the peak 1½ hours, adding an additional 40¢ to Metro. If it’s possible to commute before or after, that wouldn’t apply.

Below Nayak’s original numbers are the numbers using his per-mile calculations but doubling them for round trip, for an apples to apples comparison with Metro. The next line replaces his per-mile gas-only calculations with the IRS’s per-mile value.

The IRS already calculates an average cost of driving for tax purposes. Taxpayers can deduct 50¢ per mile for trips taken for business purposes. This is a nationwide average, combining average gas mileage (some are higher and some lower, while the heavier traffic here probably makes it lower), average gas prices (ours are a bit below the national average), average car costs and maintenance costs, and more. However, it provides a useful benchmark.

Nayak’s calculations assume a $10 daily parking rate at Metro Center, which is about the lowest it goes and requires “early bird” arrivals. Most downtown garages run about $14-20 even with “early bird,” so it would be reasonable to add another $5 (or more) to the driving costs above, which we’ve done in the last row.

All told, the commute cost using the IRS rate and a more average parking rate downtown comes out to about twice the cost of Metro even riding at the most expensive times and parking at a Metro lot.

The mistakes in the original reflect a miscalculation that many commuters are making on a daily basis. There’s a huge temptation to assume that the cost of driving is equal to the price of gasoline and it’s far too easy to forget the costs of depreciation, maintenance, taxes, fees and financing.

There are essentially two ways to understand the costs of commuting: in dollars and in time. When we think about driving as a cost in dollars, we shouldn’t think of miles per gallon, we should think of the total cost per mile. Besides the IRS’s 50¢ average, AAA’s 2010 Driving Costs report finds the average cost of driving between 36.6¢ and 92.6¢ per mile, depending on the size of the vehicle and number of miles driven per year.

And then there’s time. It’s tempting to assign a dollar value to time, and say that an hour is worth some fraction of a person’s pre-tax income, but that’s not really fair. Time is only as valuable as what you use it for.

Just because commuting by car gets a person someplace in 45 minutes where Metro would take an hour is not necessarily a better deal.There’s a cost associated with stress that different commuters place on different people.

There’s one last important consideration: What if Metro really were slightly more expensive than driving? Does it make sense for everyone to make the switch? No.

While Metro fare is fixed (at least until the next hike) the cost of driving is not. More people driving means more cars on the road and worse congestion on already at-capacity freeways. This would make commutes even longer, burning more fuel and wasting more time. A surge in demand for downtown parking would drive those prices up. So even if driving were a slightly cheaper option today as the original, incorrect analysis concluded, there’s no guarantee that it would hold if commuters made the switch.

Best of all would be to avoid having to commute from the most distant stations in the Metro system to downtown DC. No matter what the numbers, when it comes to commutes, there’s one thing we know with confidence: shorter commutes, regardless of the mode, will almost always be faster, less expensive, and less stressful than long commutes.