Hi All,

My new to me mini has been eating gas way faster than anticipated, and definitely more than my other vehicles. Calculating the MPG, i am getting about 18-20 which is 50/50 city and highway driving. Don't really drive with a lead foot in this car either.

What are some of the maintenance items i can change out to hopefully gain some mpg's back? Cabin and airbox filter have been done in the last year. Oil/coolant also changed very recently although not sure if that would even help. Alignment is in spec (running runflats still as well). Things i could think of... sparkplugs? anything else?

The car is a 2006 MCS with only 60k miles, but the age itself probably has a effect on the MPGs.

Thanks in advance!

 

I have an 06/R53 with 130K miles, getting 25.2 in mixed driving. How old are your runflats, have you check the tire pressure?

 

How old are the plugs. Should also check your BPV (by pass valve), if it is stuck open, you are on boost all the time.

 

One cannot compare manual with automatic in this era. Auto with torque converter are called slushbox for very good reasons. Way too much slippage during acceleration between gear changes. Also MPG varies greatly with city driving. In some cities like much of Portland and Beaverton the DOT implements trips a light which is most stupid. They do it because driver will just go after a while instead of waiting for the lights to go green. Sorry for going off into a tangent.

I found with high slippage slushboxes, you get better mileage if you accelerate moderately briskly from a stop so you get to the higher gear faster, instead of letting it sing "Slip slidin' away".

Here is the opening lyrics:
Slip slidin' away
Slip slidin' away
You know the nearer your destination
The more you're slip slidin' away

 

Not a whole lot left for you to do, other than changing the sparkplugs. I think MINI intent the plugs to last tens of thousands of miles - I don't recall the precise number. My experience with car is sparkplugs seldom change the MPG unless they were so neglected that causing misfire. 60k miles is quite low for MCS if it wasn't abused.

Do check the intercooler coupling boots are not leaking. I suspect your car are running just fine. I recommend taking a long highway trip and check the mileage solely on highway MPG. That will give you very good idea the health of your MPG. Slushbox automatic is lousy for stop and go driving.

 

My '03 Cooper S gets around 21-22 MPG around town and 26-30 MPG highway only driving. I've gotten as high as 33 MPG in parts of the country where ethanol free gas is available.This is calculated MPG, not car computer MPG. Car now has 145K miles and is meticulously maintained as I've been doing 5K-10K road trips the last few years since I retired. The engine is stock, no aftermarket pulleys, intake or exhaust.
We have year round 10% ethanol gas year round in the Northwest so that has an impact. I've been considering removing the injectors and cleaning them
( numerous YouTube videos available) which would probably improve the mileage somewhat but I don't think I'll ever attain the EPA figures for an '03 (25/34) since I believe they were derived from ethanol free gas.

 

Another thing to check are the coil terminals and plug wires to see if the contacts are corroded. Usually the #3 terminal corrodes for some reason on most 1st gens.

My auto, '05 with 49K, now averages around 27 mpg with a mix of regular and sprited driving. The mileage actually went up about 3-4 mpg after the 15% pulley and JCW airbox.

 

I kept records of gas usage since taking delivery of my MCS in July 2002. I've averaged 27 MPG over 72,000 miles ... with low of 17 MPG on a tank driving in San Francisco and high of 34-35 MPG on a tank cruising on the highway.

 

CSP started a thread awhile back on this very topic. It's been a good dialog of both troubleshooting and some success in reviving mpgs.

pnwR53S is right though, autos can suck the life out of mpgs.

https://www.northamericanmotoring.co...l-economy.html

 

Thanks all for the responses, will investigate based on your suggestions.

 

Numbers here seem low. My previous bone stock 2005 R53 driven spiritedly over 16k miles averaged 28.8 per fuelly. ~28mpg in the winter, and 30mpg in the summer. Not much city driving though.

 

No.....if it's stuck open, you never build boost. When the BVP closes, then boost builds.

I got pretty awesome MPG when the spring in my BVP broke.......I never built much boost.

For comparison....my 03' JCW with 150,000 miles on it gets around 20-25mpg around town, and 28-30+ on the highway.

 

I get similar with my R52 JCW manual. On the highway, if I hold it to about 65-70 mph, I can get the EPA rated 32 mpg highway (calculated).

Part of the problem is the gearing on the car, a bit stiff for the S and JCW on the highway. 3000 rpm is only 70 mph. And a supercharged car (belt driven) is generally a little less fuel efficient than a turbocharged car (exhaust gas driven).

Regards,
Jerry

 

Just topped up the tank, and running the math, Mini hog drunk 20.23 gallons and only did 189 miles of "work". 20.23 mpg with mostly in town short trips, and 2nd gear coasting thru the neighbourhood streets. Must be the damn Milltek exhaust bad influence.

 

Must be that heavy right foot you got...

 

Two big things that played into when my R52 got older and mileage went down. Check the 02 sensor, that the first one, and second is the plugs/coil/wires/air filter.

O2 sensor: https://www.northamericanmotoring.co...placement.html

 

I have an R53 Auto with a 15% reduction pulley and was getting 23-25 MPG since owned with 28k miles. This would happen no matter how easy or hard I drove it. At around 65k miles, I installed a JCW head, WMW Mild Cam , a Milltek header and the factory JCW exhaust and center pipe, my gas mileage decreased slightly with WMW quick tune. I had it re tuned remotely by someone else and now get 27-30 reliably and can get better if I didn’t live in an area with lots of hills. I now have 90k miles on my car and continue to drive and get the same gas mileage as it did with my remote tune. Most of my driving consists of open road with some city driving .

 

I changed the sparkplugs a week ago, and havent noticed any effect on MPGs yet. If anything the MPGs have only gotten worse (maybe due to 'winter gas'). I'm about 120 miles in on this tank, and the needle is already at the halfway mark. This was mainly local traffic but NYC is definitely not as hilly as other areas, like San Fran. Probably going to try to tackle the pre-cat O2 sensor next.

Here are some pictures of my old plugs, my guess is their the original plugs thus have about 60k miles on them. I havent done many spark plug jobs, but from what i could tell, everything looks normal (no oil). Was wondering, if anyone had thoughts based on the pictures below on anything to worry about?





Detailed Pics:
Cylinder 1: https://i.imgur.com/n5I3Y1c.jpg
Cylinder 2: https://i.imgur.com/Hi9xIy0.jpg
Cylinder 3: https://i.imgur.com/smimaBF.jpg
Cylinder 4: https://i.imgur.com/ZhkDHxX.jpg

 

Pull the boots off of the coil pack. Willing to bet terminal 3 is rusted pretty heavily.

Take a soft metal brush and scrub all the rusty crap off of the outside of the coil pack terminals, and the inside of the spark plug boots. Apply dielectric grease inside the part of the boot that goes over the spark plug for good measure (you can skip this step if you're trying to save a few bucks).

Don't start throwing parts at it until you're eliminated everything above the part in question within the system "tree". We know you're getting plenty of air. Too much fuel is unlikely, so I'd focus in on making sure your sparks are acceptably sparky first.

 

Thanks, just checked the plugs and terminals looked pretty shinny. Terminal four on the coil pack had some light dirt on it, but nothing that didnt come off with a paper towel.

Just finished another tank, and the calculated mpg... a whopping 18.1 MPG :(. 93 fuel as usual, and probably 2/3 city, 1/3 highway driving.

 

Something is amiss with your MPGs They should be 28 to 31.5 to the gallon.
This can be due to a host of issues. Two mini ones I have identified are shot wheel bearing packs and dragging brakes (often due to replacement of the rear brakes with out turning the caliper pistons back. Another is a tightly adjusted E-brake.
Often, the engine has little to nothing wrong with the mpgs.

Another major mpg loss is a slipping auto trans. (does not apply to stick shifts)

 

Thanks Wayne for the suggestions.

- Wheel bearing - no noise so far from the original bearings. Anyway to diagnose ones that are going out? In the past the bearings would start to make a jet engine noise.

- Brakes/e brake - I'll take a digital thermometer to the rotors/calipers after my next drive to investigate

- Slipping Transmission - Transmission gets into all gears fairly quickly and smoothly. Any other way to diagnose failing auto trans?

 

Dragging rear e brake is usually the problem when looking at the brakes. I would check out those rear cables.

Ebrake DIY 34406777400

https://www.northamericanmotoring.co...in-an-r53.html

 

I will try to answer these questions, but remember, other things will make mpgs lower than they should be!

- Wheel bearing - no noise so far from the original bearings. Anyway to diagnose ones that are going out? In the past the bearings would start to make a jet engine noise.
First off, wheel bears don't need to sound bad to be shot and here is one important thing about this: The wheel bears get warmed up and the front tires start to tow in and out, which causes drag and loss of mpgs

- Brakes/e brake - I'll take a digital thermometer to the rotors/calipers after my next drive to investigate
As ECSTuning has said: the cables for the e-brake cause drag and slightly putsthe back brakes on, which again causes loss of mpgs

- Slipping Transmission - Transmission gets into all gears fairly quickly and smoothly. Any other way to diagnose failing auto trans?
Without taking the trans out to inspect. Change the oil with Redline synthetic oil : Non slip CTV full synthetic ATF


When you remove the old oil, note if it looks discolored, as this is a sign of slipping and wear. It should look and smell good, with no burnt smell.
To just do a drain and refill, you will need 6 quarts. This will not replace oil in the converter, which can also be an area of ware and inefficient lock up, which again, will lower mpgs. Flushing system will be the only way to get the torque converter oil replaced.

Next would be valve body issues and assuming the valve body is good, it may need to have the adaptions re-done.

There are other issues that can reduce mpgs and driving style is a biggy. Along with traffic and terrain.

 

Thanks Wayne, a tranmission flush was on my "eventually" list, but guess its time to push it up in priority.

I ordered a new upstream sensor off amazon, and going to give it a shot since its a relatively (hopefully!) quick fix and will start digging into your suggestions as well.

Completely understand that comparing MPGs between different vehicles, driving styles and locations can be tough. This past holiday weekend, i put about 200-300 miles on my other vehicle (a 2017 Subaru WRX, manual transmission) all over town, similar to where the mini is typically driven. Definitely was not light on the pedal and averaged around 24 MPGs. This has me convinced the mini can do way better instead of the current 18-20mpg. Will update as parts as parts are swapped!