Originally Posted by havasu
Costco is also the only place I use the mandatory premium that my car is suppose to use. Usually, I still put regular in it and let the car's computer compensate for it.
You would save money buy using premium in your car every time. Rather than only at Costco. 1 using one tank of gas of premium doesn't give enough time for the computer to fully compensate. 2. When the computer has to retard your timing to adjust to lower grade fuel your wasting power with both the extra compression that it has that your car is designed with. But the fuel won't ignite till later in the compression stroke. Again wasting the energy used for increased compression.
You will make more power per unit of fuel. Meaning during acceleration where most fuel is used. You will have used less fuel to accelerate to the same speed. And again when cruising you use less fuel to keep the car at speed. Sure this doesn't make a big difference when your talking 10 miles. But on a 400 mile tank it starts to make a difference. Or after a few tanks.