I have an 07 SC with 5 speed AT. Installed a ScanGauge over the dashboard soon after purchase. I know what my speed and fuel usage is at all times. I continuously calibrate fuel usage and speed to be certain of accurate readings. I live in Florida, which means FLAT terrain. Here is what I have determined in 60,000 miles of driving.
1. The single most efficient way to improve mileage is to use CruiseControl whenever possible. No matter how well you think you can manually control the accelerator, Cruise does it better. And we're talkin big time better. Accelerate and decelerate using the Cruise buttons when it is safe to do so. You can expect at least a 15% increase and often as much as a 35% increase in mileage. I'm convinced that when you are in Cruise your timing and ignition advance are optimized for high mileage.
2. Speeds above 65MPH will significantly lower your mileage. The sweet spot on my car is 50 to 60MPH. In this range I consistently get 35 to 38MPG. At 65MPH I drop to 30 to 32MPG. At 70MPH I average 27MPG. At 75MPH I average 23MPG. Head on winds of 10MPH will add 2 to 3 MPG.
3. Air Conditioning lowers my mileage by 5 to 6 MPG.
4. A clean air cleaner increases my mileage by 3 to 4 MPG.
5. Lowering my tire pressure from the recommended 35PSI to 32PSI lowers my mileage about 2MPG. My SC is pretty much like driving a buckboard at the recommended tire pressure, so higher pressures are out of the question.
I have run both regular and synthetic oil in the car and have seen no difference in mileage. I drive about 75% in town and 25% on the highway and average 23 to 24MPG. A trip to South Carolina a few weeks ago at 70MPH gave me 27.8MPG from fill up to fill up.
1. The single most efficient way to improve mileage is to use CruiseControl whenever possible. No matter how well you think you can manually control the accelerator, Cruise does it better. And we're talkin big time better. Accelerate and decelerate using the Cruise buttons when it is safe to do so. You can expect at least a 15% increase and often as much as a 35% increase in mileage. I'm convinced that when you are in Cruise your timing and ignition advance are optimized for high mileage.
2. Speeds above 65MPH will significantly lower your mileage. The sweet spot on my car is 50 to 60MPH. In this range I consistently get 35 to 38MPG. At 65MPH I drop to 30 to 32MPG. At 70MPH I average 27MPG. At 75MPH I average 23MPG. Head on winds of 10MPH will add 2 to 3 MPG.
3. Air Conditioning lowers my mileage by 5 to 6 MPG.
4. A clean air cleaner increases my mileage by 3 to 4 MPG.
5. Lowering my tire pressure from the recommended 35PSI to 32PSI lowers my mileage about 2MPG. My SC is pretty much like driving a buckboard at the recommended tire pressure, so higher pressures are out of the question.
I have run both regular and synthetic oil in the car and have seen no difference in mileage. I drive about 75% in town and 25% on the highway and average 23 to 24MPG. A trip to South Carolina a few weeks ago at 70MPH gave me 27.8MPG from fill up to fill up.