What are they putting in gas today that might screw with the MPG ratio?

[The Backlash Cometh]

I filled up my tank on Sunday at $3.60 a gallon at a Mobil and by Wednesday I was at half a tank. All I did was two errands across town. Are they putting something in the gasoline to screw with fuel efficiency?

[ananda]

1. Yes.

nt

[apocalypsehow]

5. What is it? n/t.

[Horse with no Name]

2. I thought I was crazy but I noticed that too

I was thinking maybe my car needed some work or something...

[liberal N proud]

3. Was your vehicle anywhere that someone could steal the gas?

[The Backlash Cometh]

8. It's one of those caps that can only be opened from an inside latch.

[tammywammy]

4. I haven't noticed a difference

Were your across town trips in stop & go traffic? How much exactly did your mpg change? Do you have a locking gas cap...it might be time to invest in one.

[The Backlash Cometh]

9. I'm going to pay closer attention. I suggest you all do the same.

[tammywammy]

12. I fill up once every two weeks on average

It will change if I go somewhere not in my normal driving routine (like my friend that lives an hour away).

Maybe you need a locking gas cap, as gas prices go up, so will gas theft.

[Wait Wut]

11. Weird.

I was just telling my husband that I seem to be using LESS gas. I normally put $10 in with each paycheck (bi-monthly). When the next check rolls around I have about 1/4 tank left. This last check I had just under 1/2 tank. Granted, I added $2 to compensate for the bump in gas prices, but it still seems like a huge difference.

[hatrack]

6. Ethanol is substantially less energetic a fuel than 100% gasoline, but . . .

In most states it's 10%, so not sure about what caused your drop.

What's the weather like there? Unusually cold? Everybody's MPG drops in really cold weather . . ..

:shrug:

[The Backlash Cometh]

10. It's the best weather that Florida has to offer.

[ingac70]

7. Ethanol.

http://www.nytimes.com/2008/07/26/business/26ethanol.html

[tammywammy]

13. Ethanol wouldn't make that much of a difference in one week

Ethanol has been in gas forever...unless they suddenly upped the amount of ethanol all of a sudden.

[WingDinger]

20. There were calls for adding a higher % ethanol, AND they add oxygenators.

This really reduces the BTU's available.

[tammywammy]

25. There were calls, but I don't believe it happened.

They said that 15% ethanol would be okay for older vehicles, but it hasn't been set up to sell at all stations.

[deminks]

14. I have been wondering the same thing for two months. I am getting

about 20-30 miles less per tank than I normally would. Nothing has changed, and my vehicle is well tuned.

Thank you for posting.

[Bigmack]

15. Our Prius... 52mpg in Seattle... 45 in Sandy Eggo....nt

[The Backlash Cometh]

16. Rub it in.

[Bigmack]

29. Wasn't my intent... How come the diff in CA? nt

[rzemanfl]

17. I remember one holiday weekend when we filled a six gallon

gas tank for an outboard and it took like eight-something gallons of gas. We got a quick refund on that. This was on a busy highway leading to Door County Wisconsin. Easy money, cheating the FIBs I guess.

[Motown_Johnny]

18. Did you switch to a lower octane fuel?

I am not seeing any difference in my gas mileage and I tend to keep a pretty close eye on it.

[backscatter712]

32. Octane can also cause problems with mileage and power.

You should be using the octane gas that your car is designed for. If you go for the cheap regular-unleaded gas when the manual says use premium unleaded, it won't damage your car, but what happens is that because your car probably has higher compression ratios that would cause your engine to start knocking if it had low-octane gas, the anti-knock sensor will trigger, causing your engine computer to do a few things like altering spark timing and injecting less fuel into the cylinders, to prevent knocking, but also reduce your engine's power and mileage, at least until you fill up on the proper octane gas.

[necso]

19. I haven't been keeping exact track of my mileage recently,

but years ago (I used to always fill up and calculate mileage*) when they changed the formulation, my mileage went down like 10-15%. Oddly, the additive in question was supposed to decrease pollution, as I remember it.

I asked around at that time, and some other drivers had made the same observation. But it seemed to vary by vehicle, and maybe driver.

*: By doing so, I was able to identify gas stations where a fill-up seemed rather large for the miles traveled, and I have avoided these since.

[AlabamaLibrul]

21. Ethanol and other additives. I specifically seek out the one gas station that is 100% gas

and get much better gas mileage for THE EXACT SAME PRICE! Look for a Sunoco (dunno if this it's 100% gasoline nationally or not) or a little local owned, independent place. You might have one.

[The Backlash Cometh]

22. Thank you!

[AlabamaLibrul]

24. No problem - and I found you a link that might help you out

http://pure-gas.org/index.jsp

With any luck you'll find one on the list near you.

[The Backlash Cometh]

30. No prob. I'll put it on the wish list.

[Bonhomme Richard]

23. I had the same thought yesterday. n/t

[RandomKoolzip]

26. Who's "they?"

[Codeine]

27. I monitor my precise MPG with every tank

and it's been holding steady. Something else is going on, be it a short fill, gas theft, or perhaps a leaking fuel line or pump. You might also want to take a whiff at your tailpipe to see if you're spewing a lot of half-burned fuel at the exhaust.

[Statistical]

28. Ethanol. More Ethanol = higher price and lower mpg.

Still there is nothing that could be added to gas to make that much of a difference.

Either you didn't fill up (pumped clicked off but you weren't full)
Someone stole your gas.
Car/engine problem.

[backscatter712]

31. Ethanol can reduce gas mileage.

It does have the virtue of making it burn cleaner through.