Riding home over the weekend I set the cruise control on my JustaCooper to 3000RPMs, about 72 MPH indicated, and drove 172 miles, averaging 46.8 MPG on Shell 93 octane gasoline. No heater, or air-conditioning, was on. Traffic was light, no need to accelerate or change lanes often.

I was surprised, but I've often had MPG over 42 before.

 

Holy crap.

That's all I have to say.

 

Excellent!!! My best has been 39.8 in my S. That was on the Blue Ridge Parkway.

 

I, too, have seen 46 mpg in my Cooper (manual) . More typically I'm easily between 41 and 42 mpg (OBC), but that is driving around town in Arlington. The car is amazing is it's combination of economy, great handling, fun, safety, and practicality.

 

I'm topping out at 31.5. 6000+ miles now.

 

Seems hard to believe. Sounds like the kind of mileage you might get while driving 50 mph at 2300 RPMs, under ideal conditions.

You sure you weren't driving downhill the whole way ??

 

Agreed. Are you sure you filled your tank back up to the same level as when you left? I trust you aren't using the computer on the car to calculate your average fuel mileage.

 

I didn't believe the mileage either, but I calculated it by pump gallons, not the OBC. The fuel was allowed to run until it stopped. The pump was set on the first click, and the nozzle was placed exactly the same way on each fill-up. The gas gauge is pretty useless - very optimistic for the first half tank, and then it falls off a cliff. However, in all cases the fuel gauge did read full when the car was filled up.

Don't know if it made a difference, but the weather was cool and clear - it had rained for three days before my trip, and the roads were mostly dry following the heavy rain. The barometer was pretty high, we had high pressure for the entire trip.

Tire pressure was on the high end of factory recommended pressure - my JustaCooper has the 15" non-run flat tires. Just me and my wife were passengers, about 300 pounds combined, and maybe 20-30 pounds of luggage in the rear hatch area.

The OBC showed the mileage to be 49.8 MPG, but my calculated mileage was 46.8.

 

Nice record! Best I've seen was 43mpg and some change(hand calculated on Shell 93). That was on a cargo loaded, 2+1 passenger, Clubman non-S manual with a roof rack going 60mph for 283 miles.

 

[quote=lencap;2718643]I didn't believe the mileage either, but I calculated it by pump gallons, not the OBC. The fuel was allowed to run until it stopped. The pump was set on the first click, and the nozzle was placed exactly the same way on each fill-up. The gas gauge is pretty useless - very optimistic for the first half tank, and then it falls off a cliff. However, in all cases the fuel gauge did read full when the car was filled up.
quote]


lol, not the most scientific method. Try filling it up and completely topping it off....completely. When I'm on an eco-drive, I'll fill it up so I can see the fuel in the filler neck. I'll wait till all the air in the top of the tank comes out, as the gas will start to go down. I'll help this along by rocking the car. When the gas stops going down and I can still see it in the filler neck, the car is full.

It may not make a huge difference, but you're going to be getting inaccurate results as your basing your mileage off of when the gas pump clicks. The difference between a half gallon can be between 1 and 1.5 mpg. And that doesn't count your mileage being lower from carrying more weight.

400mi / 12 = 33.3333

400mi / 12.5 = 32

Not trying to break your *****....ok, I am. Cuz I'm a ****. Regardless of the technicalities, good job. To my knowledge, our car has never gotten over 40mpg.

 

thta a record... i would NEVER be able to achieve thta

 

What was your route? (Start and end point?)

 

Nice!

Coming home from AMVIV yesterday, from Belen, NM to Carlsbad, NM via Roswell, I managed a hand-calculated 40.7mpg using 90 octane crap-gas. 289 miles, filled 7.1gal in my Cooper S. I'm sure a lot of it was downhill, but for me, that's still pretty good.

 

Very good numbers. I have seen 42 on the computer of our Jusa a Clubman(the computer has allways show almost exactly 2 mpg more that the measured number) and I just say 34 on my new S hard top but it only has 400 miles. I can wait to see what the difference between s and non s turns out to be.

 

The route was I-85/40 from roughly Charlotte to just past Raleigh, NC. The OBC showed combined distance (miles remaining in the tank and miles travelled) of 718 miles; I've never been close to that before.

When the pump stopped, I topped up as far as I could, both when starting out and when I filled up.

Could I have been wrong, sure, but 718 miles projected on the OBC suggests that my mileage may be close to accurate. I can't explain it, just reporting what I observed.

 

OBC sits at 46.1 at the moment driving around town, but I am working w/ the lights. Sometimes I hit the lights right, sometimes not. Either way, the Cooper is doing pretty well.

 

I don't want to be critical because you seem to have done everything correct in measuring and calculating your mileage. In my experiences with my '06 MC and other kinds of cars I've never seen that kind of mileage on anything but a VW deisel. I had 5 Honda Civics over a 20 yr period and the highest I ever saw was 38. I usually check every tank except during the depths of winter when mileage can dip down into the 20's. My Mini has averaged 35 on reg and premium with a high of 39 once which I ignored as a fluke in filling the tank.

 

Good point.....only the second gen Cooper ('07+) is can get numbers like that (consistently over 40 mpg). First gen car and second gen car engine has big differences so it's hard to compare.

Not to worry though...first gen eclipses second gen in some other important areas.

 

Pretty much.

 

Yeah, that's pretty much the "nature of the beast" with all cars. The only cars I've owned where the 1/4, 1/2, and 3/4 hash marks were correct were ones where the hash marks weren't spaced evenly.

On my Mercedes, there wasn't even a needle's-width of space between "full" and "3/4". Then the space between "3/4" and "1/4" took up 85% of the gauge, and there were maybe two needle-widths between "1/4" and "Empty".

The two main culprits are the fact that the fuel-level float in the gas tank usually can't "float" all the way to very top of the tank. That's why you can usually drive for quite a while before the needle even comes off "empty". Then there's the problem that the cross-sectional area of the tank isn't consistent from top-to-bottom. This means that the distance the float drops per gallon of gas used isn't the same throughout the tank. Most tanks have their biggest cross-sectional area near the middle, which is why the needle moves much more slowly between the "3/4" and "1/4" marks.

 

My previous personal best was 48.7 mpg in my 07 justacooper, shell 93. A saturday morning trip to the dealer. 20 miles of two lane deserted highway running 55 w/cruise, no ac, then 80 miles of interstate running at 65 w/cruise. Real early morning, only one stop light the whole way.

This years trip to the dealer I beat that. OBC said 50.5 when I got to the dealer. I was floored. Had a weather system and probably had a 20 mph tail wind the whole way. On the way back it dropped from there with a 20 mph head wind, but combined round trip was 48 mpg.

 

I thought the air-conditioning units in modern cars nowadays don't affect the fuel economy??
but i do know windows down at highway speeds affects it

 

I suspect the 176/65-15 non-run flat tires are critical to those mpg numbers.

 

I'm not all that savvy about cars, but why does a manual get better mileage than an automatic? I would think the automatic would shift at just the right time with no unnecessary engine revs in between. I know the weight of the auto transmission is a factor, but is that the only reason?

 

Wow those numbers are amazing. I'm glad to know giving up my Civic won't make a difference in gas mileage.