Gas prices may have come back down to Earth, but with summer on the horizon they're sure to make their annual climb just in time for your big road trip. The American Automobile Association (AAA) expects the average nationwide price of a gallon of unleaded to jump 50 cents this summer. Seasonally soaring prices and a still-sinking economy mean saving money on every fill-up is as important as ever. ¶ None of us can control the price at the pump, but there are ways to keep consumption in check and money in your wallet. After almost three years and nearly 100,000 miles on the road during my Trans-Americas Journey road trip, I've found these gas-saving tips have proven their worth time and time again.

1. Say yes to free gas

A trend that exploded during the sky-high price hikes of 2008 continues with many hotels, car rental companies and other travel services offering gas incentives such as the Road Warrior package offered by New York City's 70 Park Avenue Hotel (www.70parkave.com), which is part of the Kimpton Hotel Group. The Road Warrior package includes deluxe accommodations, a $20 gas card and free nightly parking (a $52 value) from $229 per night through the end of 2009. The Drive & Dine program at the family-friendly Sanibel Harbor Resort & Spa (www.sanibel-resort.com) in Sanibel Harbor, Fla., includes deluxe accommodations, daily breakfast, kids under 12 eat all meals free and a $25 gas credit per night ($159 per night through Sept. 30).

2. Cool it

Before using the air conditioner, crack the windows slightly to give hot air a place to escape. This helps your car's interior cool down more efficiently, which reduces the power drain on your engine caused by a chugging air conditioner. And use the re-circulation function instead of constantly sucking in new hot air from outside the vehicle.

3. Fill up on the rez

American Indian reservations are exempt from many state and federal fuel taxes. This usually (but not always) translates into better prices at gas stations on reservation land. And there are other bonuses, too. When I filled up at the Moccasin Trail Center gas station on a Chippewa reservation in Odanah, Wis., I got $5 in free play at the neighboring Bad River Lodge & Casino (www.badriver.com) for every $20 I spent on fuel. If it's your first time at the casino, they'll throw in an additional $5 in Casino Cash.

I put $80 worth of gas in my truck and Transfer Flow (www.transferflow.com) auxiliary tank and got $20 in Casino Cash, plus my $5 first-timer bonus. After seven minutes at the slots, I made back $16.50 and suddenly what had been an $80.34 fill up dropped to a much more palatable $63.84.

4. Start faking it

I was skeptical, but within a couple of months after switching from traditional motor oil to synthetic motor oil (I use Amsoil, www.amsoil.com), my gas mileage showed a small but solid improvement. Synthetic motor oil lasts longer between fluid changes, so you save on garage visits, as well.

5. Pack light and keep it inside

According to AAA, a loaded roof rack can reduce your gas mileage by 5 percent. Keep everything neat and tidy inside your car by staying organized and maximizing space. The Mountainsmith Modular Hauler ($59-$129; www.mountainsmith.com; click on "travel storage" under "products") is a system of heavy-duty but lightweight nylon cubes that hold a ton, have clear plastic sleeves for easy labeling (snacks, toys, guidebooks and maps, etc) and pack into a hauler with handles for easy stacking and moving.

6. Ask a local

I was in Marquette, Mich., at lunchtime and stopped at the Rice Paddy (www.eatricepaddy.com) to fill my stomach (not the tank). Over a lovely zesty green curry with chicken, I asked the owner, Aoy LaChapelle, whether I should fill up in bustling Marquette or wait to get gas in the much more remote Upper Peninsula area, where I was headed. To my surprise, she assured me gas would be cheaper outside Marquette. And she was absolutely right.

7. Give 'em your card

Most supermarkets issue free gas reward cards to accumulate money off at the pump with each supermarket purchase. I've saved hundreds of dollars on gas over the North American portion of my road trip using Safeway's Power Pump card which, like many cards, allows me to earn gas rewards not just on groceries but also on gift card purchases. But be warned: Rules vary and card-issuers reserve the right to change terms and conditions without notification. For example, I didn't realize it when the Power Pump program imposed an expiration date and I lost more than $100 in accumulated pump rewards.

Karen Catchpole is in the midst of a road trip through North, Central and South America. Read more about it at www.trans-americas.com.