I recently went from an '02 MCS to an '04 MCS.

I have noticed that the gas mileage in the '02 was WAY better than the '04. When I would reset my computer when refueling the '02 would read nearly 400 miles on one tank. (roughly upper 300's). In the '04 it is just barely over 200 miles per tank. What gives here?

I also noticed that this car burns through gas as if it were an old 1960's muscle car.

Is there anything I can do to increase my mileage per gallon? Anything I can look at or replace?

 

Hmmm. I have an 06 JCW. I average about 300 miles a tank. On my recent vacation, I was able to get over 400 miles a tank. Lots of straight, traffic free roads in Nevada. Cruise control paradise.

Get a can of Sea Foam to pour into the tank with your next fill-up. Clean out your fuel system.

How's the air and fuel filters? Those can affect your mileage somewhat.

 

I have an 06' MCSm.
I get 420-440 mi per tankful... averaging between 31-33mpg.
Most (nearly all) of the driving is highway.

I'm assuming that the new 04 is stock and your out of warranty... so I'd check the filters (air and gas) first, then run a can or 2 of Cheveron fuel cleaner through...

if that doesn't clear things up, then I'd start checking to see if your 02 sensor is still good or that there is a vac. leak after the air-flow sensor...
you could pull your plugs to see if your running rich...

If the car is not stock, more air and fuel in means more power... and worse mileage.

Also check you tire pressures (and sizes) to make sure that they are correct.

let us know if this helps...

 

1. first and foremost, drive like a granma in a ford fairlane. low accelleration and minimal braking mean less gas burned per mile traveled
2. full tune-up if you haven't already
3. get some really boring tires and inflate them properly.
4. keep your windows up and a/c off (enjoy that, right?)
5. be sure you're using 91 octane or better
6. agree w/ gromit, you should be getting 300mi/tank or about 24mph.

 

I think there is still some warranty left. I have yet to check the fuel or air filters. I can check the air filters, however I've no clue where the fuel filters are or how to clean or replace them. Regarding the plugs I'd have no idea to tell if it was rich by looking at them.

The car is stock bumper to bumper. I have yet to check tire pressure or sizes. I'm not sure what you mean by sizes, but I'll make sure they are the same size they are supposed to be!

Thanks for all the help. I'll let you know what turns up!

 

I would be interested in the fuel filter location also. The Bently Manual(I have found not so accurate) says it is a non servicable item and in the fuel tank as part of the fule pump/pickup assembly.

 

Roeri, check to see if anyone in your local club has a Scangauge II that you might be able to borrow for a bit. This will allow you to see, in real time, what is going on. You may be able to diagnose this without paying the dealer. I'm assuming, since you didn't mention it, that you aren't getting any SES codes.
Possible causes:
Fouled plugs, stuck bypass valve, dirty air filter, underinflated tires, vacuum leak, or any of a number of different things.
You really shouldn't be seeing much, if any, difference between this MINI and your old one, if your driving pattern and habits have remained the same. I agree with the above posters who suggest a good dose of fuel system cleaner. Seafoam is great, so are Lucas and Chevron.

 

Nuthin' kills gas mileage like a bad (or getting bad) O2 sensor.

 

I don't believe the R53 has a replaceable fuel filter - not that I've seen yet, anyway.
By sizes he means that if your tires are significantly larger than OEM (205/45-17 or 195/55-16), the odometer will read low - you would be going farther than you think you are.
200miles is definitely lower than normal range.

 

Well, I dumped some Lucas into a full tank and already noticing a difference. I assume just by logic that I wouldn't see an immediate gas mileage increase. But I will say that the engine seems more 'calm' than it was. Much softer when idling and it seems to accelerate at a more brisk pace. I have yet to check/change the air filter and I've heard the same thing regarding the fuel filters. Tough to get to/expensive to replace.

I'll keep you all posted on the progress!

P.S. I am LOVING the Lucas. I recommend anyone get it as you will audibly notice a difference!