Yesterday we came to the conclusion that Al Gore can’t achieve his goal of minimizing energy usage simply by outlawing drive-thru windows.  That was a macro analysis of using drive-thrus, but what about on the micro level?  How much does it cost you and me?

I’ll take an average person and apply a reasonable maximum and minimum cost associated with letting your vehicle idle while waiting at a drive-thru.  Obviously, those who visit drive-thrus frequently and have less fuel-efficient vehicles will experience a higher cost, while those who rarely visit drive-thrus and have more fuel-efficient vehicles will experience a minimal cost.

First, we’ll use some numbers from yesterday.  The most fuel-efficient vehicles consume 0.25 gallons of gas per hour (gph), while less fuel-efficient vehicles consume 0.30 gph.  These two numbers will represent our min and max.

How many drive-thru visits do you make a week?  If your answer is 0, then there’s no drive-thru cost to you, and you’re no longer eligible to play our game.  If your answer is 1 or more, then read on.  I’ll let 1 be the minimum, and 5 be the maximum.  (Five visits may sound like a lot, but it seems plausible enough for someone to make two trips to the bank/ATM, and three trips to get a Big Mac each week.)

How long does your vehicle idle while waiting in the drive-thru line?  As we discussed yesterday, it could be as quick as 1 minute, or as long as 10 minutes or more.  For an <I>average</I> time of all weekly visits, I’ll use 2 minutes for the minimum and 5 minutes for the maximum.

For today’s exercise, we’re trying to determine the cost to an individual so we need to account for the price of gas.  Today, the average NC price for gas is $2.40, but only a year ago it was much higher at $3.94.  For simplicity, I’ll use a low price of $2 per gallon and a high price of $4 per gallon.

That’s all we need to determine the annual cost for an individual.
If you have a fuel-efficient car, are quick, can buy cheap gas, and suffer from drive-thru-phobia, the annual cost from letting your car idle in a drive-thru line is very small, near the value of $0.87 per year.  On the other hand, if you drive a gas hog, get in line behind a drive-thru customer paying for his order in pennies, buy expensive gas, and the McDonald’s cashier knows you by name, then your annual cost is nearer the $26 amount.

What does all this mean?  It probably means I need to get a life.  It also means that we shouldn’t let concerns about gas consumption determine whether we use the drive-thru or go inside.  If we want to do our part to reduce carbon emissions and contribute to a greener future, then we won’t be getting many brownie points just for avoiding drive-thrus.