Last year when I filled my car I could go 356 miles until empty, now when I fill my car it says 321 miles until empty. What is causing me to get less miles to the gallon?
Less Miles to the Gallon on 2007 Lexus ES350
Your driving condition and circumstance. When the outside ambient temperature drops the fuel economy is affected, in your region and most of the country, during the winter months we have oxygenated fuels that run cleaner in cold temperatures, but cause a lower fuel economy. Prior to your fill up, if you were driving in stop and go traffic for most of the ignition on cycle, your trip computer is basing the range on the mileage it calculated in that stop and go traffic. If you were on the highway and going down hill most of the miles prior to your fill up the range might show up as 450 miles. The miles to empty is a calculation based on your driving habits and current average mpg. I hope that helps you understand.
I agree with irvtech. Also wind will affect gas mileage because any serious headwind can take several miles per gallons off.