Was getting 14.5 MPG around town and limited freeways.
Now about 15.5. I think that Southern CA went to Winter Mix fuel maybe.
Must be some reason for the MPG increase.

I never floor it.
Never pass anyone.
Try to use brakes as little as possible.

I drive the Rover like a Prius for MPG.

Find that one a back road - 40 MPH is good as seems the torque convertor is locked and the RPMS are low on the tach.

On the highway I never go past 55 MPH now.
That pizzzes off people but that is what the RED fog lights in the rear are for.

Plus driving it easy is better for tire wear and the transmission.

 

So what’s the difference between summer and winter blends? Well, it’s important to note that butane (4 carbons) is relatively cheap. Molecules with more carbon atoms are more valuable since it’s easier to break molecules down than build them up. Which means that refineries looking to make the most money want gasoline blends that have the most shorter chain molecules while still having a mixture that is stable enough not to evaporate during the distribution process. It’s also important to note that butane has less energy by volume than longer chain hydrocarbons.
In the summer, it’s warm out. Which is nice for swimming, but bad for living in a world where we have tanks of hydrocarbons all over; zipping around us, stored in our garage, buried at gas stations, airports, and vehicle fleet facilities, etc. When it’s warm, things evaporate easier, and shorter molecules evaporate easier than larger molecules (they are more “volatile”). Reducing the volatility of gas cuts evaporative emissions, which contribute to ground level ozone and related environmental and health problems. So regulations were put in place to protect us and dictate that summer blend gasoline have to effectively be heavier (less volatile, more longer chain molecules).
In winter, it’s cold, and so refineries are allowed to produce gasoline that evaporates more easily. So they maximize the cheap, low energy butane in the mix. Any benefit of your car starting more readily is really limited to old and/or poorly maintained vehicles. Current vehicle technology is pretty hardy.
What’s the result? Well, basically, winter blend gasoline has a larger percentage of butane in it. And since butane is cheaper and has less energy, winter blend thus costs less and gives us a lower MPG when we burn it. So it’s a wash, right? Eh, maybe. Your vehicle miles per gallon typically will drop 2-8% when you start filling up with winter blend. Unfortunately, evidence suggests that the common price decline is 2-4%. Of course this price change can easily be lost in the noise of a global commodity. So you should probably just make sure you’re car is running optimally (oil change, tire pressure, reduce weight, clean off snow, etc. ) and cross your fingers on breaking even from a cost per unit of energy point of view.
*Unless your vehicle manual says differently, using a higher octane rating

 

I don't know I would stop driving it until you can figure out that problem. Continuing to drive could cause you to get used to spending less on gas....

 

I'm getting around 14 in town 18 on the highway. If driving through down town probably like 10ish.

 

i get about 13 town 20 highway (i drive 80 on the highway and use cruise control) not sure how i get 20 to be honest but thats what i calculated off a 350 mile road trip. During winter if you use summer grade you would think you would get better mpg due to it taking longer to evaporate.

 

I recently installed the Torque app on my android phone and set up two gauges with average and instantaneous mpg readings. I found that by watching the instantaneous reading and modifying my driving I was able to improve my milage from 15.5 to almost 20 on the highway. It definitely does not involve driving 55 though, that is about the worst thing you can do. It's all about momentum. The sweet spot seems to be right around 70 mph for my truck. I was able to consistently get over 19.5 average both directions to and from work which involves virtually no level ground.

 

My D2 V8 4.0 used to do about 12 mpg in town and 18-19 mpg on a flat highway. In the mountains or hilly roads probably less. Highway driving seemed most economical around 70 mph but when taken up to 90-100 mph the fuel gauge went down as fast as the speedometer went up. They are thirsty beasts when driven hard.

 

Geez! I'd be happy to get 14 mpg's! I get about 12.5 on a consistent basis in my '99. Wife gets about 13.5-14 in her '04. Now granted, I know I need to do a few things... clean the intake, change the O2 sensors and such. But you guys claiming 18-20 almost sounds absurd to me.

 

Confirmed with precision yesterday, half the time city, half the time at 50 mph on country road, got 17.2 mpg, at 50F ambient, 175F coolant, autopilot off, driving gently.

When the red fuel light came on (flat terrain), zeroed the trip odometer. Put 5.00 gallons of 87 octane, and lasted 86.1 miles until the light came on again.

Will come back with freeway-only figures when I have them. Very confident will be above 20 mpg.

 

As far as I know, using ECU and GPS data I am looking at very accurate readings. The computer knows exactly what the pressure is in the fuel rail and exactly how long it commands the injectors to open. The GPS is probably accurate to within a few feet. If you've got over 100k on your O2 sensors the first thing that's going to happen is a significant drop in mpg so that would be my priority. Eventually they are going to start throwing codes and activating your CEL..