Many people will say that accelerating slowly is a good way to get better mpg, but that actually isn't the case. What works the best is to accelerate quickly into second gear, the slowly build up speed from there. Cars are least efficient when they are running at really low RPM, low speed, and low torque. You need to spend as little time as possible around the lowest end of the spectrum. When you're at 0 mph, all the gas being used just keeps the engine running, and it's not used to overcome external forces (friction, weigh, air resistance, etc...) at 5 miles per hour, the jeep is running at very low rpm, and most of the gas is used just to keep the engine from dying. Once you hit 10-15 mph, you're primarily overcoming the normal force between your car and the road, and almost no gas is used solely for the purpose of keeping the engine running, that's when you should stop accelerating as rapidly and let the car slowly gain speed up to the cruising speed.