I've had my 05 JCW for a couple of months now and I expected mileage that perhaps wasn't the best as I got used to the car. (The sound of the SC is very addictive at first ) Now as I have settled in and my driving habits have normalized (usually shifting at 2250 rpm) I am still getting a calculated 18 MPG (OBC says 19.1). My driving mostly consists of 2-3 25 minute round trips per day in suburban traffic. My car only has 26K on it and other than a cold start stumble that has just popped up in the last week the thing seems to run like a champ.

Is this something I should be concerned about or is this just a fact of life for an R53?

 

Check your airfilter. Also, check the spark plugs. If you are shifting at low rpm and not really getting on it, you should be at least 24-26 combined mileage.

Also, the cold start rpm rumble is normal.

 

Sounds like you should wait till 3500 rpm or more, and only cruise at 2200 at min.
You might want to reset you computer...from the dash, and let it relearn you driveing habits... What it knows now is that you are sorta lugging the motor, and it my be running very rich to make enough power to keep moving.
I have a regular s with a 17% pulley and JCW inj, and I get about 26-28 mpg highway, and about 19 or so around town....on 93 octane.

 

Shifting at 2000-2250 the engine isn't struggling at all. I mean it's not like I'm going uphill in 5th at 2000 RPM. I haven't had a chance to pull the spark plugs yet to see how rich it is running though. I had been meaning to try and reset the computer to see what kind of difference it would make, I'll give that a shot tonight.

My car doesn't see the highway a whole lot (maybe once a month) and our city mileage numbers are pretty similar. I was kind of hoping to have better city numbers though because heck my 69 510 got 22-23 mpg in the city.

 

When I do mostly city, shifting easy, I easily see 24 MPG. I also do the skip shift method. 1-3-6, shifting at 3000 rpm.

 

I do this a lot around town too. Definitely easier on the car, and the driver!
I have about 30,000 miles on mine.....

 

Not that it is the reason for your poor mileage, but a 2250 RPM routine shift-point seems borderline lugging to me and I suspect driving around like this all the time could be detrimental to the engine bottom end long term. The engine seems a lot happier at 2K and above and in normal driving, 2K-3.5K is the everyday range I'd suggest for smooth engine operation and decent mileage.

Your mileage is low, not ridiculously low, but lower than average for the type of driving you do as described. The suggestions to look at the air cleaner and plugs are good.

If your highway mileage is Okay (and mid- to high-20's is typical), then I'd chalk this up to your driving conditions. Are you doing lengthly warm-ups? Suburban driving means different things to different people.

- Mark

 

If I were to hit 3.5k in first then 3.5k in second I would already be exceeding the speed limit. But I'm willing to give it a shot.

I'm not too sure that the air filter would the culprit. About 1200 miles ago I had service 2 done at the dealership they replaced the paper element with a K&N unit. Reading the plugs on the other hand should at least give a clue if the car is running rich.

I don't really have a number for highway mileage as I don't usually hit the highway.

As far as warm-ups go I usually let the car idle just long enough to clear the fog from the windows which is usually 30 odd seconds with a quick blast of AC. Although within the last 7-10 days I usually let it sit an extra minute to let the idle smooth out from the cold start stumble.

Suburban driving for me is the kind of driving that's 30 mins outside of Vancouver which consists of 26 stop lights and 4 stop signs (counted on google map) in a 25 minute round trip. Speed limit 50 KPH.

 

Then I don't think your mileage is out of line.

- Mark

 

I didn't mean to imply that you should consistently hit 3.5K on every shift. Just generally keep the engine in the 2K-3.5K range in normal driving. If you're shifting at 2250, you're probably dropping below 2K pretty frequently and 1st gen cars are pretty rough below 2K.

- Mark

 

its 100% driving habit. Dont use the brakes, and your MPG will be over 30 every time.
If you have to use your brakes, you are accelerating too fast and not looking far enough ahead. use the engine to slow down by lifting, not downshifting. Keep proper air pressure in your tires and you will be good.

 

its the stop lights that are killing you. also what wheel and tire package to you have? if you have S-lights and eagle runflats like mine you will get terrible in city mileage. I get 32mpgs all highway and 28-30 mixed extra highway. in Pittsburg, KS where I go to school I am averaging 19mpg going back and forth to class. I hate it! once I get on the highway though it picks back up. way up. If I cruise at 35mph in 5th gear I will get about 40+ mpg on a 4 stop short trip (approx 5 miles). it is really all about getting to speed without pounding the throttle and getting to about 3K RPMs then skipping a few gears. get to cruise quickly and cruise as long as possible but be as smooth as possible as well. I hate driving for efficiency but it is a great skill to acquire.

 

I'm running 215/40/18 Hankook V12 Evos on some aftermarket 18 inch rims. I was told the rims are 19-20lbs but havent been able to verify for myself. This setup isn't as light as running some 15s but should be a little bit lighter than S-lights and runflats.

I haven't had a chance to run through a full tank of gas while using the suggestions posted here but oddly enough the OBC is showing a drop of .5 mpg. I'm not sure how that will translate into a real world number though. I think overall I have to chalk my MPG to the rather annoying number of traffic lights in my area.

Oh and I found an old article the other day reviewing the 2005 JCW. It listed city mpg at 19.8. So I guess I'm not really that far off the official number I just figured with other people claiming high 20s and even low 30s I might have had something wrong. I'll probably have to find a clean regular Cooper if I want better economy for this kind of driving. Then I can save the JCW for sunny weekends.

 

A very smart man once said it was more fun to drive an underpowered car car hard, than a powerful one gently!! Having owned both I can say I agree to a certain extent!! Have fun....now go motor!! More gas is both cheaper, and more enviormently sensitive than getting a second car.....(less embodided carbon, etc).

 

Noz you must be really short distances between lights. I can get my MCS down to 19mpg if i have 1 mile jaunts. unfortunately because of the nature of the supercharger these cars take a lot more fuel to get moving. however once they are moving and no boost is required then the resistance goes down and you get very decent mileage for the engine design. honestly I wish I could make the R53 engines direct injection. in my opinion they would be considerably more efficient than the newer engines. that extra control of fuel mixture and better atomization of the fuel would yield amazing results on the older engines. and a COP setup would compliment that as the old waste spark ignition that is on these is a little out dated.

 

My .02

Poor mileage can be a combination of things but usually it is mostly driving habits. Good posts above, I agree with those suggested tricks. Use the instantaneous MPG setting on your computer to see what works best for you. Generally you want to get into top gear as soon as you can without accellerating too heavily. To do this you need really good low end power. I find those magnetic fuel system gadgets (clamped to the fuel rail inlet) increase fuel atomization and gives you that low end. After installing it you will find the car is really easy to get off the line at a lower RPM and also it will instantly have a really smooth idle. No difference in mid or upper RPM range. It gives you the tools to run it at a lower RPM, works on every car I have tried it on.

If you take a page out of the hybrid manual and cut the engine at stop lights and get everything else right you can easily get highway mileage even in bumper to bumper traffic.

09 JCW 33MPG city 35.9 HWY (@80MPH+), B4 magnet mod 29.5-31MPG city
05 MCS 29.5 city 34+ HWY (wife has a lead foot)

 

very serious here. what type of magnet system are you using. I have personally tested many of the ebay units for fun to absolutely no avail. you seem to have had a considerable increase. details about the actual units you are using and pictures of their installation on both of your cars would be very appreciated.

 

I've owned my '06 JCW for almost two months and I've been getting 25.5 'combined' and 27.5 on the highway. I'm not hard on the car but I don't 'undershift' either. I live in a rural area so I drive about 7 miles @ 55 mph before I really hit stop and go traffic and even then its not that bad. Like the OP, I too have around 26k on my car.

I was a little disappointed at first, coming from a '05 C230 Kompressor that saw 29 mpg mixed and 34.5 on the highway, but if you do the math, the out-of-pocket difference is a drop in the bucket.

 

Magnet details:

I am using the one from Harbor Freight, full price is $19.00, but I have seen them on sale for $12 before. Keep in mind what it does and you take advantage of that to get the increase. Also make sure you have the magnet on the inlet to the fuel rail and not the outlet. When you add it the idle should be noticeably smoother. Almost night and day, a big difference. If not maybe switch fuel lines and see if that is what is going on. Also it should be really easy to start the car moving (manual trans of course) on flat ground with little or no throttle. When stock, the car dies pretty easily when you try this. It is that low RPM, when there is not much airflow to atomize the gas where the magnet goes to work. If you add it and drive like normal it won't really make that much difference.

Also for 09 JCW drivers, note the torque curve how it jumps steeply at low rpm, drops off and then builds back. Take advantage of that curve and drive at the lower torque peak which is I believe at around 2k? This is the reason the turbo gets so much better mileage than the supercharged version. The torque peaks at a much lower rpm, and lower rpm is what saves gas.


Smoke 05S
JCW 09
MCS 05

 

.... which is absolutely nothing. Fuel magnets have been debunked over and over and over again (not surprising since fuel is totally unaffected by magnetic fields) - strictly snake oil.

- Mark

 

amazing that folks still buy that crap. Anybody want to recomend the tornado thingy?! Magnets on a gas line is almost as crazy as having an actor as a Governor, or running a state goverment by printing IOU's!

 

I get 15mpg

Don't know how you guys get 20+

And yes my filter is brand new, iridium ngk etc...

 

I got 27 mpg out of my last tank strictly "mixed" driving (zero interstate - rural highway and regular city/stop & go). My car seems to like Shell's premium gas better than all the others.

 

I usually average around 20 mpg on my 03' R53 sometimes higher than that but with the way i drive at times and the constant highway driving of 70+mph in stretches I tend to get about 260 miles out of a tank. I did notice the other day that i burned through a tank of shell gas a lot quicker than the BP(300mi) though, which is kind of odd(I must have been driving Miss Daisy or something).

If you're really that concerned about fuel consumption then it probably would have been better to get a "Just a Cooper" and not an S. But what's the fun in that?

 

Wow I had all but forgotten about this thread.

After some more time to keep an eye my mileage numbers I've come to the conclusion my fuel consumption is a result of living in a somewhat hilly area and what I gather is short distances between lights for a suburban area. From what I can tell it's an average of 1/4 mile or less between lights.

I've noticed a couple of things in the process of watching my fuel. Since switching from 94 octane Chevron to 91 octane Esso my cold start stumble in the morning has completely vanished. We had a bit of a cold spell about a week ago (around 20F) and according to the OBC my mileage dropped from mid 19s to mid 16s. I guess this is telling me the engine never had a chance to fully reach proper operating temp. Lastly leaving the heater fan on its highest speed from the night before is a real drag on a cold morning start.