According to fueleconomy.gov, the combined mpg difference between the Cooper and Cooper S is about 3mpg (29mpg vs 26mpg), which is what I would expect for a higher-powered turbo engine over a regular NA. However, my question is, in your guys’ estimation, how much of that mpg difference is due to the S’ wider tires? I see the base model has 175 width tires, whereas the S comes with 195 width tires. So if I got a base model and then equipped it with 195 width tires, how much should I expect the gap to narrow between Base and S models' fuel economy?

 

I would say little to none, I've run different tire width on many of my cars and never noticed any significant MPG change. The bigger difference would actually be in the reason the MC has different tire size than the MCS, it because the MC has 15" rims while the MCS comes with light weight 16" (standard). Normally the smaller the rim the lighter the wheel (to a point, you also have to factor in tire weight), but I think in this case the 16's are actually lighter, so would actually be more beneficial to fuel economy (but again very small).

Also if your planning on simply changing the tires on the MC to 195s and not getting 16" rims you have to factor how that will effect the odometer and Speedometer.

http://www.miata.net/garage/tirecalc.html

 

I don't know where the differences come from, I know I'm not the most economical driver out there and I see no significant difference in economy between our two. There was a small bump in the gov fuel economy ratings between 07 and 08 (for reasons I've forgotten) so when comparing them I don't know if its the difference between an 07 and an 08 or MC vs MCS.

I run the same tires on both of them (205/50-16). The biggest difference in economy is you never have to push an MCS, it just goes fast effortlessly. In the MC I tend to push a bit harder to get the performance.

 

I have a MC (I'd hardly call it a base model though!) and I have about 15,000 miles on it after a year of ownership. I put premium fuel in it all the time, and I do a combination of highway and city driving. On the weeks that I am mostly on the highway I average close to 48mpg. During the break in period the mileage was considerably less... but I have never had a tank yield less than 41mpg in the past 6 months. I have the stock tire size and blaster star alloys.

 

...But those are "Canadian" mpg's, right Carlisle? We use Imperial gallons here in CA which are greater in volume than the US gallons.

You can do a "quick and dirty" (not exact, but close enough) conversion to US mpg by subtracting 20% from your Canadian numbers. So that's about 38 mpg on the high side and 33 mpg on the low end for all you U.S. readers.

I have about 13000 miles in 10 months of driving and average about the same fuel mileage as you. I also have the 16" Star Blaster wheels and stock Conti runflats. I have used both premium and regular fuel and haven't noticed any difference in mileage or performance between them.


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I have the MC auto and I get a consistent ~34.5mpg on mixed driving. I have the base 15/175 tires.

 

RIGHT! I totally didn't realize that we use the British gallon and that one of our gallons is equal to 1.20 USA gallons... is that correct? Most ppl my age use the metric system. Anyone older than me uses the imperial system. We used to use the imperial system of measurement as a country, and switched to the metric system maybe 30 yrs ago when Pierre Trudeau was the Prime Minister. I use the OBC to measure the mpg instead of the km to litre ratio.

This is just another point for the metric system... at lease it is standardized! (and easier to work with)

I measure my driving distance in km's, but I like my fuel usage in mpg!

But to give a "Canadian" perspective... I drive between 725 - 825km on a tank of premium 91 octane fuel. I have honed my driving style to be super thrifty. I think that is about 475 miles on a tank? give or take?

 

Well... I'm not sure I like that "older" comment ... ... but I grew up with the old "Imperial" ways. The metric system is easier to understand (kilomneters, meters, kilograms, ets.), but I've always measured my vehicle's fuel economy in mpg. "Liters per hundred kilometres" means nothing to me.

Just as an aside for you young whippersnappers who understand liters, 1 US gallon is 3.8 liters... 1 Imperial gallon is 4.55 liters.

725 KM is 450 miles, 825 KM is 512 miles, FYI. I get about the same range as you, depending on my driving habits. Although, I just filled up this morning (87 octane regular grade fuel) and my OBC says range is 860 KM (533 miles). Gotta like that!!


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I have a 2007 MC (6-speed manual) w/17" Crown Spokes and ~26K miles on the stock Conti run-flats (205/45-17).

When the tires were new, I was getting 34.5 mpg daily average, and 38-39 mpg on the highway. Almost exactly at 4K miles, my daily average dropped 2-2.5 mpg and stayed there (~32 mpg).

Last winter (Dec. 2007), I put my Michelin X-Ice's on for the first time (185/65(60? can't remember...)-15 mounted on the original 15" wheels). It turned out that we only got snow for one day, so I ended up driving the better part of two weeks on pavement, and my mileage went right back up to 34.5 mpg - swapped my 17" wheels back on, and ta-da, right back down to ~32.

So, the rolling resistance of a particular tire (and/or run-flats in particular?) and how it changes as it wears are definitely factors to keep in mind.

 

Imperial sucks. Metric is the way to go. L/100km makes so much more sense...

I'm averaging 7.2L/100km on winter tires (which should have a noticeable effect on fuel economy), in almost exclusively city driving. 2008 MINI Cooper, 6-speed manual, premium fuel. That's just a tuck under 40 mpg, and about 33 Imperial mpg.

 

i dont know about tire width, but I did notice a big difference in mileage with tire compound. I switched from runflats to the Goodyear F1 Allseasons and saw about a 4mpg difference. I drive mainly highway with my 07 MCS and used to average 38mpg with the runflats, and now I get 34mpg.

 

The tire width is not going to make any real difference. A wider, shorter contact patch will have very marginally higher rolling resistance, but probably not measurable. The tire compound and tread design will make a difference.

 

Not sure about tires (I still have my original set on my 5/07 manual Cooper) but my mpg has never failed to be well above the official #s. I've never gotten below 40 mpg in city driving.....right now my OBC says 46 mpg (also strictly city). Regardless of any fudge factors between OBC and actual, the results are still very good!

 

gokartride,

40 city/46 hwy? My 08 showed numbers almost like that (38/44) until I reset the language to English (US). Then it came back to about 34/38, which meshed with my manual calculation.

If you're already set to US, then you must have a hypermiler big toe.

 

I've found the milage on my 08 MCS to depend on driver technique to a huge extent. It's really easy to lean on the throttle, gets lots of acceleration and burn lots of gas (less than 30mpg). However, I've also seen 40+mpg using the cruise control on long, flat highway doing 60 mph.

 

While we're on the subject of Base vs S gas mileage, do you guys think the automatic climate control affects the base engine more noticeably than the turbo's gas mileage? Under modestly warm weather conditions, I know the AC compressor must be engaged, but is it "fully engaged"? Meaning, that the AC compressor for the automatic climate control is sapping the same amount of engine power regardless of whether it's 100-degrees outside or only 70-degrees? Is it always gonna feel like the engine's struggling because of that?

I'm asking these Base vs S questions because I'm trying to decide which one to get for my daily commuter. Being that I'd like the automatic climate control and some 16" wheels, I'm just wondering if the combination of these two things will sap the Base model's engine so badly that it's no better than the S in terms of gas mileage, and that I'll be lugging slowly around everywhere I go.

 

I would expect that the Climate Control will only engage the A/C when it's needed to maintain the selected temperature within a certain number of degrees, so there shouldn't be a continual performance ding with the CC turned on. If anything, there might be less of a milage ding since the CC will automatically turn off the AC, while I tend to keep the AC on until I'm too cold.

I also don't think there will be much of a difference between the 16" and 17" wheels. Since the tires on the 17" are lower profile, both wheels will have nearly the same overall diameter. I've driven both the 16" and 17" and there is no dramatic difference in acceleration and milage between the two. There is a cornering difference, tho.

 

Yea I have automatic CC, I've only seen like a 1-2 mpg difference from summer to winter (when the compressor is never on , I make sure to keep it off).