For long road trips, is it cheaper to rent?

Monica wrote in with a question that I thought deserved a detailed answer.

I’m going to be driving from northern Minnesota to Dallas, Texas for a week this summer, then returning home. I own a 2008 Toyota Corolla with 34,000 miles on it. I’m trying to figure out if it’s more cost effective to rent a car for this trip or to drive my own car.

It’s going to be really hard to find an exact answer for you given the variables, but I can give you a good estimate that should guide you.

First, let’s get some numbers. I’m going to assume that you live in Duluth, Minnesota, so the length of your trip is 1,100 miles. We’ll assume that you’re going to drive 300 miles while in Dallas, so your round trip will be pretty close to 2,500 miles.

A 2008 Toyota Corolla gets 29 miles per gallon, according to fueleconomy.gov, which is my source for such data. At your current mileage (and making some default assumptions about your Corolla), it’s worth $11,282 according to Kelley Blue Book. After the 2,500 miles of driving, your car would devalue to $11,182, which means that the road trip would devalue your car by $100.

You’re also going to be on the hook for half of an oil change if you drive your own car. It also pushes you along on the rest of your maintenance schedule, which is difficult to estimate but does have a significant cost. Commute Solutions identifies the maintenance cost per mile for driving a car as being 5.3 cents, which means that over the course of the trip, you’ll rack up about $132.50 in maintenance costs (including oil changes).

Now, if you’re renting an economy car, you’re going to be paying about $250 for the rental for the round trip. I looked at several different rental companies that function out of Duluth such as Hertz and Enterprise and found several different estimates for a weeklong trip. I did use coupon codes to get those quotes.

A 2011 Chevy Aveo (the “example” economy car that is mentioned on Enterprise’s website) gets 30 miles to the gallon, compared to the 29 mpg of your current car. That means, over the course of the trip, you’re going to eat up three more gallons with your own car, costing you about $12.

Now, if you were to get a 2011 Toyota Prius for that “economy” price, you’d get 50 miles to the gallon, compared to the 29 mpg of your current car. That means, over the course of the trip, you’re going to eat up 36 more gallons than with your own car, costing you $144 (assuming gas prices are at $4 this summer).

In this example, then, the cost of renting a car with a similar fuel efficiency to your own is roughly equal over the long run. The catch, of course, is that many of the costs associated with your own car are delayed. You don’t pay for the maintenance now and the depreciation doesn’t affect you now. Those things impact you later down the road.

However, if you rent a car that’s significantly more fuel efficient than your own, you’ll likely save a little money by renting. Again, the costs of renting are up front, where many of the costs of using your own car are delayed.

Of course, this all depends on the rental rate you’re able to get and the car availability. If you’re able to lock in a highly fuel efficient car in conjunction with a strong coupon or other offer, you may find it cheaper to rent. Otherwise, you’re probably better off driving your own car on this trip.

In the end, there are some factors that make renting a more appealing option: a long trip over a short time period, an increase in fuel efficiency, and the availability of coupons or other discounts makes renting compelling. Without at least some of those factors, though, I’d lean toward driving the car I already had, and if the costs were close, I’d use my own car because of the lower hassle.