By Justin Boyle

Some years ago, a schoolteacher friend of mine and I took six weeks during the summer to drive around the United States. We had a few destinations on the schedule, but mostly we just appreciated scenery, took detours, slipped through a few back roads and enjoyed the journey.

By 2006, gas prices had spiked to $3.00 a gallon. They've had ups and downs since then, but scarcely has the price of regular unleaded settled below that mark for any remarkable period of time. In summertime especially, when refineries have to switch their process to produce lighter fuels, gas prices can be downright scary.

Fortunately for would-be road warriors, some credit companies are helping to bring back the open road by offering cash back on gas. Credit cards with gas promotions are more common than you might think, and we'll look at a few examples that can help you afford to ramble the highways without completely turning out your pockets.

The best gas rebate credit cards

American Express Blue Cash Everyday and Blue Cash Preferred

Both of these cards offer choice rewards for the highway traveler. The reward structure focuses on gas and groceries, which are two of the biggest expense categories on a road trip.

Let's take a look at a breakdown for each:

Blue Cash Everyday Card from American Express

• 3 percent cash back at at US supermarkets, up to $6,000 per year in purchases.
• 2 percent cash back on gasoline at US gas stations and select US department stores
• 1 percent cash back on other purchases.
• Terms and limitations apply.

Blue Cash Preferred Card from American Express

• 6 percent cash back at US supermarkets up to $6,000 per year in purchases.
• 3 percent cash back on gasoline at US gas stations and select US department stores
• 1 percent cash back on other purchases
• Terms and limitations apply.

For both offers a few notes: cash back is received in the form of Reward Dollars that can be redeemed as a statement credit and terms and restrictions apply.

Just from looking at those numbers, it seems that choosing the Preferred card is a no-brainer. Blue Cash Preferred does come with a fee of $75 per year, though, so Blue Cash Everyday might be for you if you prefer to carry cards with no annual fee.

Chase Freedom Visa

The Chase Freedom benefit structure is set up to reward those who plan ahead to best take advantage of the categories when they are promoted.

PenFed Visa Platinum Cash Rewards Card

It's almost as if PenFed created this card with road trippers in mind. Not only is there no annual fee and a small cash back percentage on all categories of purchases, but your variable APR starts, if you can believe it, under 10 percent.

Of course, this PenFed card wouldn't be on this list if it didn't offer great gas rewards: 5 percent cash back on all pay-at-the-pump transactions in any state, at any time of the year. The catch is that this particular Visa is restricted to members of Pentagon Federal Credit Union, but you can apply for membership after making a donation to a qualifying organization.

Tips for hitting the road

Even with the best gas rebate credit cards, it's no inexpensive proposition to see the country roll by your window at 70 miles per hour. It helps to save a little first, and check your vehicle's gas mileage against how many miles you're trying to go. A little budgeting can go a long way toward avoiding unexpected complications once you're on the road.

When I took my own trip, credit card rewards programs weren't as common or fashionable as they are these days. If they had been, and I'd been smart enough to do some research, I might've been able to squeeze at least another week out of the experience. I guess I'll just have to do it again.