Some reasons why fuel economy decreases in winter Winter Tires: Winter tires are notorious for losing mpg as their tread patterns often create more resistance to the road that summer and all-season tires. Winter Gasoline Blends: The change in winter fuel blends affects economy as well, in order to have fuel work in cold temps and prevent freezing etc. economy will sometimes suffer. The difference between summer- and winter-blend gasoline involves the Reid Vapor Pressure (RVP) of the fuel. RVP is a measure of how easily the fuel evaporates at a given temperature. The more volatile a gasoline (higher RVP), the easier it evaporates. Winter-blend fuel has a higher RVP because the fuel must be able to evaporate at low temperatures for the engine to operate properly, especially when the engine is cold. If the RVP is too low on a frigid day, the vehicle will be hard to start and once started, will run rough. Summer-blend gasoline has a lower RVP to prevent excessive evaporation when outside temperatures rise. Reducing the volatility of summer gas decreases emissions that can contribute to unhealthy ozone and smog levels. A lower RVP also helps prevent drivability problems such as vapor lock on hot days, especially in older vehicles. The switch between the two fuels happens twice a year, once in the fall (to winter-blend) and again in the spring (to summer-blend). The changeover requires significant work at refineries, so oil companies schedule their maintenance for those times when they will already be “down” for the blend switches. Excessive Idling: It is common for people to let their cars idle longer in cold weather to warm up their car, engine, and clean off their windows of frost. Windows can be easily scraped, while most new vehicles do not require to idle in the winter to warm up, they can be driven right away and warm up on the way to where you are going. Seat heaters and defrosters: The alternator is turned by the engine using a belt. So basically what happens is the engine has to work harder to turn the alternator that is working harder because you are using the seat heater and defrosters which are using more than normal electricity. So, when the engine is working harder it is using more fuel. Characteristic of the seasonal change: So remember if your car is well maintained by your favourite technicians, there may be nothing wrong with your vehicle at all it may just be a weather influenced situation.
Written By Perry M. Mason