I have been driving a Mini for three years. Recently my gas mileage has dropped from 39 mpg to 29 mpg. The dealer's service department says it's because I'm using gas with ethanol in it. Do you guys think this is true?

 

If you are using gas with ethanol in it than yes, this is most certainly why you are seeing a decrease in MPG.

Not all cars can run on ethanol fuel, only those that state from the factory that they are E85 compliant, which would mean that they can take a mixture of ethanol/gasoline that is pre-mixed. Not all states have this fuel yet, but if you are filling up with this stuff, you will see a loss in milage, as well as performance. You should use ONLY 91+ octane gasoline, specifically from a reputable station if you can.

If by chance you don't know that you are using ethanol, or feel that you are not using an ethanol mixture, then I have no idea what could cause it other than needing a tune-up...

Drew

 

i normally try to drive under 3000 rpms in the city. That's the only way i can drive during this break in period. We are getting around 22mpg ...

 

In our area they are starting mix in 10% Enthanol. Its hard to avoid.

 

I am all for the economic/environmental benefits of using ethanol, but I can't see how it is allowed for them to mix it in to regular gasoline since most engines haven't been tested and therefor aren't setup to run on ethanol. Hmmm... I hate it for you guys, and I'll have to watch out when I come to MD from now on I guess...

Drew

 

I find it hard to believe that using a blend of 10% ethanol with the rest premium grade gas can exact a 10mpg penalty.

(If you are filling your car up with E85 that's a no no. The MINI is not -- AFAIK -- spec'd to use E85 which is 85% ethanol and 15% gas.)

In times past, when driving out of CA to parts east and then back again, I"d notice an increase in gas mileage once away from the rotten CA gas (back when CA used MTBE and most of the country didn't), and then of course a decrease in gas mileage once I returned to the CA area, but the change was maybe at best a few miles per gallon.

Engine performance changed too, getting better going east, worse back in CA.

Nowadays, most every place I drive only offers a blend of 90/10 gas/ethanol so the mileage doesn't change much -- due to gas blends -- when I leave CA for points east. (Mileage picks up because I do quite a bit of freeway driving and little city stop/go driving but I know the car's mileage when highway driving on crummy CA gas and take that into consideration.)

If you're using a name brand quality 90/10 gas/ethanol gas and seeing a 10mpg drop off then something's wrong.

Even accounting for perhaps getting a tank or two of "stale" gas, that's a big hit in mileage. (Advice is to buy gas from stations that do alot of business and are less likely to have "stale" gas in their tanks. Gas can go stale in just days, too.)

You sure tire pressures' are ok? You haven't loaded trunk of car down with junk?

Oh, if you've started using the A/C a bunch, that can account for a drop in gas mileage, but still, 10mpg is a bit much.

Sincerely,

RockC.

 

The way I understand it, every gas engine built since the early seventies can handle the 10% ethanol mix with no worries about engine damage. As RockC posted, you should definately not be using E85 in a MINI.

 

I trust your measurements for the sake of this thread, but it's also worth going back and remeasuring your mileage for a few tanks of gas, just to make sure that it wasn't a temporary thing. Also, it's possible that the original 39mpg figure was somehow inflated. Again, I don't mean to imply a lack of trust here, but it's worth mentioning.

As Ran48 said, almost all modern gasoline engines can handle a small percentage of ethanol mixed into the fuel (no more than 10%-15%, which is what a lot of stations have now). I can't think of anything in addition to what's been mentioned. Keep in mind that 29 mpg still isn't all too shabby, but I'm sorry to hear your MINI has suffered such a precipitous drop in mileage. Hope you're able to diagnose/solve the problem yourself, and good luck!

 

Maybe the on-board computer is out of whack, if you are using that as your guide. You can reset the trip odo next fill up and calculate the MPG the old fashioned way at the following fill up. I've read somewhere on this site about the on-board computer being a bit "off" on things of this sort.

swizzle

 

My first question would be how was the 39 mpg arrived at? Computer calculation or actual miles driven divided by gallons used? My personal experience is that the on-board computer is pessimistic - actual consumption is about 1 - 3 mpg better than the computer says.

Ethanol blending can cut mpg by around 2-ish mpg as was posted earlier. Add in heavy a/c use and you could lose another 2 - 3+ mpg. Carrying around a bunch of stuff (people or things) can lose another 2 - 3 mpg. Net, net, more information is needed about the operating profile before conclusions can be reached.

 

Don't recall ever hearing of someone getting 39 MPG in their Mini. I'm with swizzle, sound like your on board computer was/is not accurate.

 

Not sure how you accomplished 39 mpg but it sounds pretty good to me. Worst case I get 25 mpg city and besr case 35 mpg highway.

I drive a 05 MCS six speed and no cruise control. I fill up with Sunoco's high test 94 Octane.

Last weekend I drove at relatively high speed 130 km / 80 mph - 160 km / 100 mph for 500 km / 312 mile highway journey from Ottawa to Toronto to see if I could burn off a tank of gas . I used up 46 litres / 10.5 imperial gallons. Result 29.7 mpg.

I love the MCS ! $55.00, 500 km, 4 hours of pleasure. What a way to travel.

BRG

 

Um, prob has a MC not a MCS...I've heard people getting into the 40's with a MC with highway driving...

 

This thread died but I'm having problems and I don't think it has to do w/ the gas that I use. (Shell, Chevron, & or Conaco)
To keep this one short, I poured the wrong stuff in the tank, used heat and went 3 to 4 tanks still averaging at least 30-32mpg. I then put the right stuff (RedLine Injector Cleaner) in the tank and I dropped down to 25mpg on the hwy Grrrr....I've been told that it is the gas that I use, but I just don't buy that. It happened when I put the injector cleaner in and it's bugging me. Also, I'm trying to cancel out things that I don't think could possibly change it that much.
I'm thinking that it is an O2 sensor? and or the injector 0-rings? I've also wondered if maybe my muffler needs to be replaced? Maybe? Has anyone heard of a muffler going bad after about 76,000?
I've ordered injector rings since they are a lessor $$$$ item, and have been told that to much injector cleaner and or most brands will eat up the o-rings.

If anyone can help me out here I would greatly appreciate it!

 

Has anyone else had this happen and or something similar to it that can help me out?
Your .02 cents is appreciated

 

Not to rehash an older thread - but noticed in my MCS about a 4-5MPG drop in the last month.

Possible that the combination of 10% ethanol and cold weather is to blame? Any thoughts on this? I know ethanol doesn't like the cold and generally will hurt mileage, but a 20% reduction?

 

in a completely unscientific test - Ethanol is useless

Recent trip to Vermont resulted in the following OBC results for mileage using
Shell V-Power fill up in NH and VT.

Full tank of 10% Ethanol Blend - 22.1MPG (very poor)
3/4 Tank of NON Ethanol (approx 2gal of 10% still in tank) - 25.4MPG

Same highway - the return trip was acutally a little worse as I had to hop onto backroads and traffic and STILL had better milage without Ethanol - Guess it's time to get a few steel drums and make a trip to VT for good fuel.

 

I have an 02 MC and get terrific gas mileage. If I get on an Interstate, I can get up to 37 or 38 mpg. But, the ethanol does promote an decrease in mpg. At least, it did for me. Unfortunately, I think the 10% mix of ethanol w/fuel is supposed to be in effect eventually for the entire country...isn't it?

 

I've had my 05 MC 5-speed about five months, and back on October 30th (prior to the winter blend fuels) upon fill up I calculated that I almost hit 38 mpg. Three-fourths of the tank was highway motoring (~70 mph average) and one-fourth was commuting to work, including a bit of afternoon stop-and-go beltway traffic. I'm absolutely convinced that I can achieve 40 mpg or more during summer highway motoring if I could just keep the rpms below 3500 for a whole tank (but it's so darn hard -- my MINI considers such conservative motoring to be quite unnatural ).

BTW, I hand-calculate each tank and keep a log in my GbT...it's fun to keep track, and I figured it might give me an early indicator if something mechanical starts going south...

My last fill-up was on Dec 29th. All DC beltway driving. 433.4 miles on 12.6 gal = 34.4 mpg Makes me perfectly happy to pay for high test!

 

BTW, I hand-calculate each tank and keep a log in my GbT...it's fun to keep track, and I figured it might give me an early indicator if something mechanical starts going south...

I do the exact same thing and it has helped me idenify problems a little earlier than usual. I also use the log to keep track of the many mods!!!! ;-)
Motor On!

 

I've noticed my MCS drop from 28 to 24 MPG lately, but I think it is due more to the weather getting colder than anything else. Read the manual about gas grades. It states 91 octane recommended for summer driving. But does that mean mid-grade is fine in the winter?

 

Arch -

I would be reluctant to use lower octane fuel at any time of the year. Seems like the burning rate properties of the fule in the cylinders would be similar for any season once the engine warmed up to its nominal operating temperature, but perhaps the actual, sensible temperature of the fuel coming from the tank makes a difference, and that would account for the recommendation in the Owner's Manual. Anyone out there with amplifying information???

 

It boils down to energy per liter or gallon of fuel (and purists will correct me on the actual calculation and data for Octane Ratings, do a search if you want the details), but relating to E85 versus Gasoline versus 90/10 or 85/15. The issue is that Ethanol does not have as much power per gallon, so you burn more to go the same distance. This is similar to "winter mix" gasoline for those of us "lucky" enough to live in a cold climate. All winter mix is bad, keep the higher octane. E85 and ethanol blends are not more environmentally friendly (yes, look it up), but they are politically friendly. Basically you are burning moonshine, made here in the good ole US of A instead of imported oil. I know it's more complicated than that, but that's it in a nutshell.

 

Ethanol actually can be a better fuel than regular gasoline. 10% is fine and dandy. it is an oxygenate. Oxygen helps burn gas. that's what an engine does.

Water in your gas increases octane rating and horsepower. Odd right?

ethanol and water kill your car however. anything more than 10% can corrode, any water, of course, corrodes. I learned that "gasoline" is just a random crap mix of certain solvents, additives, flammable gunk that is set to a standard of burning.

100 octane is like a massive amount of toluene. Methanol can be added to your tank if you set it up for racing like a nut with a lot of cash to blow. Acetone can clean out the car and raise octane rating as well possibly damage hoses so it's not that great.

all in all, bottom line is that your car is ****ed up. My MCS with local driving mostly, some speedy driving, some chill driving, gets above 23 miles per gallon. On the highway i get little over 30 right now. it is brand new so gas mileages are lower than expected for highway driving. Your MC should be getting near 35 local and 40+ highway.

I noticed that rpm's mean little to the 1.6 litre engine. While of course the lower the rpms the less gas is consumed, it doesnt amount to as much difference as you would think. Acceleration blows away gas in a cooper it seems, not 3k-3.5k rpms like other cars.

 

How are you defining "better" in that statement? Energy content in one gallon of gasoline is 124000 BTUs. Ethanol is 75700 BTU/gallon. That is a measurement of the chemical energy stored in the molecular bonds. Just for comparison, Diesel has 139000 BTU/gal. This is from the EIA.gov site.

Based on those energy yields, ethanol is not a "better" fuel than gas or diesel.