Our Saurer 6dm just made a three day trip to Panama City Beach, FL. We were around 4mpg at 57mph, weighing in around 28,000 pounds. Those high-speed axles everyone crows about, well, think about it for a minute or more. Our usual pace is 50mph, a big difference in fuel mileage versus 57mph, as the rpm's increase from 1700 to 2200. We high-tailed it as an A to B route on the freeways to get here. Usually, we don't do that, and take a more relaxed two lane highway trip. Having a lower gear ratio, like in a Jeep going from 4.10 to 3.73 might be the answer. However, like the owner mentioned, you have to weigh the costs of that plan versus the fuel mileage you get at what the manufacturer put in your vehicle. For us, a Swiss-made vehicle, changing out the ring and pinion front and rear, it's not worth it. Also to consider, what will the drive-train put up with going down the highway at 65-70 versus a cruising speed of say 55? Also, why be in a hurry?
