Fuel-efficient vehicles are not only cheaper to rent, but they offer more miles to the gallon saving you considerable amounts of gas money.
Bring only what you need when driving. Heavier loads weigh the car down and cause resistance. Another good reason to do this is to avoid theft. Maui thieves target tourist rental cars with lots of stuff visible.
You've seen it on Hawaii bumper stickers. Speed on the road is something only mainlanders abuse. Keeping your speed down will lower your gas consumption because of the decreased drag. If you take it easy and follow Maui residents' example, you'll fit in and be treated with aloha. Also, quickly accelerating and breaking will use up a lot of gas. Keep it slow and steady.
I know this one is a tough one. But if you open your windows, you'll get the Maui breezes to cool yourself off. Keeping your windows open will increase your fuel economy by ten percent over using the A/C.
Make certain you've rented a well-maintained car with fully inflated tires. Having a junker rental can eat up even more money in gas than the extra cost of a newer rental.
Maui is the best island in Hawaii. You'll be doing a lot of driving if you do it right, so take heed to the tips above and you'll be fine. There's far too many wonderful drives to do on Maui, so suck it up, buy the gas, and drive slowly. See you on the road in Maui, Hawaii!