Hey Guys,

I have a 2006 v6 mustang and I have a concern with my gas milage. I use to live in Indiana where I would get about 20mpg. Since I have moved to MD I have noticed that mpg has dropped to 16 mpg. This sucks, I purchased a v6 for the better MPG since I didn't race but now I am getting just as bad as the GT.

I drive about 10 miles a day and half of that is on the highway. But even in the town, the RPMs hardly ever go over 2000rpms. It gets to about 2100 when on the highway, but that is about it. I have made it a point to make sure this is true as a test. But what doesn't make sense is that I am getting less MPG then when I would drive for an hour at 70MPH at 2600-2800rpms.

Thoughts?

I bought the car used. I have never done a tune.

Thanks.

 

I would start by cleaning your intake filter or buy a new one. After that if nothing happens then replace you fuel filter. Sounds like you need a tune up. How many miles do you have?

 

I have about 83k. I am confident the air filter is good as I replaced it this past summer.

 

It most likely is the winter blend fuel.

 

What is in winter blend fuel? I live in Indiana and it gets colder there than in MD. Which doesn't make sense geographically but true.

 

Gasoline doesn't vaporize readily at very cold temperatures. So oil companies formulate fuel differently for cold-weather markets in the winter. Unfortunately, the changes that provide better cold vaporization characteristics also result in less available energy for combustion. You won't get as far on a liter of winter gas as you will on a liter of summer gas.

 

Cold weather + winter blend gasoline* + short trips** + city driving = lousy mpg.
*As per others, more butane is added in the winter than in the summer to lower the fuel's vapor pressure, and butane has less energy content than gasoline. However, the volume of butane added to the gas also varies from state to state. Thus, one of the reasons your mpg is lower in MD than it was in IND is because MD may be adding more butane to its gas than IND.
**5 miles one way is considered short in cold temps, because the engine takes longer to reach normal operating temperature than it does in warmer temps. This causes the A/F ratio to stay richer and the idle rpm to stay higher for a longer time, which eats more fuel than when the engine is fully warmed up. Plus, half of your trip is city driving, which eats much more fuel than highway driving. Also, your daily drive in IND may have been longer and had less city driving, which gave you higher mpg.

Finally, your vehicle gets better mpg when driving for an hour at 70 mph because of the reasons stated above. The engine is fully warmed up for most of that hour(45-50 min.), and highway driving gets better mpg than city driving(unless you do a steady 120+ mph).

 

Winter blend is used in more heavily populated areas so you may not have encountered it in Indiana.

My first thought/question is, are you doing more stop-and-go traffic (stopping at lights or slowing down, accelerating, slowing down, etc.)? It takes a very little increase in having to accelerate to result in a big change in fuel mileage. Variations in % ethanol will also influence average fuel mileage.

Other than checking your tire pressure, cleaning your TB, changing your fuel filter and ensuring that your air filter isn't clogged, it's most likely your environment and NOT your car.

BTW, who'd you **** off that you moved to Maryland? J/K. Maryland can be ok as long as you're not in any of the metropolis's. I grew up in Philly and I'll never go back to ANY major city.

 

I think it is more about your driving style. I'm not saying you've got a lead foot, just that 10 miles is barely enough time to get the car warmed up, and until the car is warmed up, the fuel maps are extra rich for safety. In short, the car pumps more fuel until the car is warmed up.

Another thing it could be is an oxygen sensor that's seen better days.

 

This, too. Short trips are murder on average fuel mileage #'s.