I have something thats baffling me about my MCS.
I live in Atlanta Ga and drive to Dallas Tx once every month.I always drive the 785 miles @ 75mph, setting the cruise control. I20 all the way......
I always get 31.7 mpg going to Dallas but always get 30.3 mpg coming back!!!
I cant believe that its uphill all the way back or that the wind is blowing against me so what could it possibly be????
I have done this damn journey 8 times and the same happens everytime

Im baffled!!!

 

I get between 25 and 28, so you're doing something right! I've gotten 29.8 ONCE, but that was commuting to work on 2 lane roads and deliberately taking it easy. My car drinks gas on the interstate at 75 or so. I get better mileage on two lane roads running 50-60. Until I saw your signature, I expected you to have a stock 02-04, but you have an 05 with a 19%, etc. Mine's a JCW with the same wheels as yours.

Have you noticed a similar mileage differential in other cars on the same trip?

Rawhyde

 

I have only done this journey in my MCS

 

You're going downhill to TX - uphill to Atlanta - simple physics add in the east/west windflow and there's your answer.

 

Krut

Forgive me, I am a little geographically challenged but to the best of my knowledge Dallas and Atlanta are at similar elevations and the predominate wind flow in the Usa is West to East isnt it?? If that is so then my mileage should be better coming back to Atlanta??
I know this seems like a meaningless thread But I was just a littled baffled by the whole thing

 

Maybe the good doc (Dr Obnxs) will chime in with a theory. He knows a thing or three about physics. I'm just a mechanical engineer (and a gearhead) and I have no clue. Once or twice is a fluke, but 8 times...I think you're on to something.

Rawhyde

 

I know this is a complete stretch and sounds like something out of start trek but heres goes.When I am travelling west to east I am going with the earths rotation Right? The earth rotates at 1000mph approx And I cant drive quite that fast so is it even possible that the miles stretch a little due to this????????

lol

 

Depending on what day of the week you travel, there are either more big **** trucks heading West or, more big **** trucks heading East. There is a suction created by the trucks breaking wind at 75MPH, which tends to pull your little car along. If you released your accelerator and coasted to a stop you would notice that you would coast a bit farther down the road than if you coasted in the opposite direction from the largest herd of trucks, a test not recommended.

 

I've got a 2006 MCS and get 27mpg but that is more due to the terrain around Missouri, small hills like a roller coaster between home and work and the fact that I like to hear the SC whine so I get in the throttle a little more then normal. I've tried checking at cruise on a longer trip with flatter roads and was getting 32mpg at 80mph so the car is capable of doing better then what I'm getting normal right now. I can't avoid the fun factor of 6000+ rpm with the SC spinning a great tune and the accelleration you get from our little rocket cars.

Motor on!

 

Another theory to the mix. You should be using right about two tanks of gas going and coming. Since I assume you fill up in Texas, you may be getting a poorer quality gas, reducing your MPG for the first leg of your return trip. Maybe next time, rather than averaging the whole trip, average for each tank and see what pops up. Another thing to consideris temperature and humidities effects on the efficiency of the engine.

Basically, your 1.5 MPG difference can be due to a lot of factors, especially since it's A) very small and B) well within the measurement errors of the computers. Assuming you are using the OBC, of course. If the computer is adjusting to environmental conditions just slightly, that could cause it.

Or if you want to go with a terrain defense, maybe the uphill battle coming west to east is steeper, or less steep but longer than the other way around. Best advice, average each tank and compare so you can narrow down the geographic location a little better and maybe someone can come up with yet another theory.

Better advice, don't worry about it!

 

Sorry, but its the wind, and the few hills.

 

Just a guess, but have you thought about what gas you are using? Do you get lower octane, or go to a different type of gas station in Texas? Maybe the fuel is better in Atlanta? Just a guess though...

 

Hmmm. The nature of the undulations in a road make a difference. Not just the net elevation change. Any given hill can have a steeper climb and less steep descent, or vice versa. Hence the combination of grades of the climbs one way might be of a nature that effects mpg differently.

Also, buying gas for the return trip out there, might be the car likes one a bit more than the other.

If you drive really really fast then as you approach a measureable percentage of the speed of light mass starts moving towards being infinite and I'd guess a tank of gas with higher mass would provide more energy so... Of course if you start REALLY moving 'briskly' the red shift will get you and all traffic lights will appear red due to doppler shift, and stopping for all those doppler created red lights will kill some mpg too.

Edit: Sorry, others brought some of this up while I was typing mine, so some repitition of ideas

 

My contributions:

1. Different brands of gas produce different mileage.
2. Gas station pumps gallons used not accurate.
3. Time of day. Going in the morning and returning in the evening? Maybe temperature/humdity could be affecting your mileage.
4. Air conditioning cycling differently if your returning in the warmer afternoon
5. Refilling is not being performed exactly the same (trapping air, not filling completely.

 

Maybe after being in Dallas, TEXAS, your MINI really need to drink more after the experience. Traumatic I'm sure.

 

I happen to like this explanation!

 

The Gas quality theory is interesting Cant think of a better one right now
Thanks for the inputs

 

The gas station could also be ripping off the customers. I heard on the news last month that 9 gas stations in my city were fined because the pumps indicated the customers were pumping more than they were actually getting. One customer simply swiped his credit card and it IMMEDIATELY showed that he had pumped half a gallon. Um, he hadn't even put the nozzle in the tank. The gas stations are hardly any more honest than Big Oil themselves.

 

If you fueled up here in Houston you would get like 40mpg instead... j/k
are you sure that they are relative in elevations? I know geographically speaking they are on the same line but east texas is a much flatter place. Dallas is considered hill country BUT as you know Atlanta lies in the mountains. I think your fighting an uphill battle

 

The elevation at Dallas Tx is 430 ft above sea level. The elevation at Atlanta Ga is between 738 - 1050 ft above sea level depending on were in Atlanta you live. You would in fact appear to be going uphill.

 

Hey, guys...this thread is about two years old....INTERESTING, but still old... I wonder if the OP is still around and if he ever figured it out?

 

I would have my opinion but the thread is too old