i have an 03 with a 15% pulley,intake,exhaust,dtbpv,occ and tsw v2 damper and im pulling 29.7 according to the obc but i get over 300+ per tank and i have the 17" R90's...you might want to consider a ecu reset...have the car relearn for your driving style....but you might want to also look at the coil pack and plug wires...after i swapped my coil pack for a new one and msd wires i gained milage as well

 

Artoo is an '03 with about the same mileage. My OBC consistently says 22 in town and I get about 30 averaging 70-75 on the run from my house to Summit Point which is about 250 highway miles. The bottom line is that you are probably in the ballpark with 24.

Rich

 

One biggy to help mileage: Check and set the tire pressure. Don't assume that whoever had it before you set the TPM with correct pressures in the tires. Oh, yeah, I get great mileage for a few miles on the way to work and then the corners show up...
-skip-

 

I've been through three tanks since I started this thread, with the following results: OBC: 24.7/Actual 23.5, OBC 25.6/Actual 24.2, and OBC 25.8/Actual 24.3. I guess I'll try some new plugs next...
BTW, this is still way better than the 14 mpg my truck was getting - not to mention WAY more fun!

 

I'm trying to figure this out too...I'll try to change to the 15% pulley plus intake/exhaust and wheels and we'll see

 

There's just no way. Not even an R56 S can get that for city driving.

 

if your OBC is as bad as mine has been.....

Matt

 

My OBC reads around 40 at 60 mph in sixth on a flat highway. I've never done a complete tank like that, of course.

I've found my OBC is pretty close to what I actually end up calculating, too. one big tip to increase mileage - coast up to stop lights and stop signs. too many people run up on them and then slam on the brakes.

I can get over 30 on a tank if I really, really try. Usually, though, I get bored with trying after about half a tank, and end up at 26 or so!

 

I just filled up again this morning, and it's (Gasp!) down to 21.3 actual! I was pretty P.O.'d until I realized that last week my wife borrowed the car and did me the "favor" of filling the car up. I called her and asked her if she put premium gas in it and, of course, she said, "Why would I do that? Regular is 40 cents cheaper!"

 

<captain obvious>is there a clue there? </captain obvious>

i'm surprised! that tempts me to guess there is a pretty direct relationship in your case between octane and mileage. i'm surprised because i'd have guessed (apparently incorrectly) that the knock sensor is not retarding the timing on a healthy MCS even with 89 octane fuel.

one way to check it would be to try a tank of the best fuel you can get, and see if that produces a gain (of course you have to have invariant driving habits )

am i wandering off the reservation here folks?

one note: the air cleaner "looks clean" is somewhat an assumption may i say? i do not know how much flow loss occurs on an element before it looks dirty (just my ignorance). you might know better.

(just for data, my JCW is also pullied of course - i forget what the % is. i was getting 26-27 quite consistantly until two months ago when i stumbled across a mileage thread. i tried shifting up at 3k unless i needed power, and since then i've had a consistant 30 with a max of 32.9. in my case the shift point gained me 20% more mileage. of course since max torque is at 4k that is like having a beautiful lover and vowing chastity!)

 

is to log timing.

The stock MCS pull timing on 91 octane, the best we get here in CA (usually). This is just another data point in the evolution of motoring. When cars weren't governed by knock sensors, running the lowest octane you could without ping was the cheapest way to drive. Not so much now.

Dropping 40 cents a gallon with a 10% drop in mileage is a wash here in CA, without even thinking about the performance drop....

Matt

 

this sounds stupid... but i've always gotten meh mileage in my 06 mcs. Some times great and most of the time average.

well otw to amviv i followed my buddy who has a cooper and doesn't drive like an idiot like i tend to... i ended up with insane mileage that i had never gotten before. I just need to stay out of the gas more i guess. I just had a bad habit of sinking my foot into boost every time i needed to make an adjustment in traffic on the highway. Thus proving that a carbon unit adjustment can some times be the best tune up.

 

I've found mileage to be about:
1. Your right foot, this is the single largest impact. Like food, anything fun is bad!
2. Tires and pressure (wide summer stickies are bad, narrow hard tires good)
3. Aerodynamics
4. 2 vs. 4 wheel drive (a 4-5 mpg hand up on my Audi)

 

So... here's the basic facts: any fuel-injected car conforming to emissions standards of the last 10 years burns 98 to 99 percent of it's fuel. That leaves 1 to 2 percent to play with using aftermarket addons or whatever. If the engine is running well, in tune, and not worn out, there's not much left to gain. Driving technique will have probably the biggest single effect of anything you can do.
Dragging brakes, slipping clutch, low tire pressure, or poor alignment all directly effect mileage, too. I don't think there's any single 'magic bullet' answer to good fuel economy, but rather a bunch of little things that can be done. IMO.
-skip-

 

Might want to check your gas; if 93 octane is achieved with a lot of ethanol additives, your mileage won't be nearly as good as use a 91 octane with little or no ethanol. If you are interested, do a little google search on ethanol and mileage - if ethanol producers admit that the mileage can be much worse (flex-fuel drivers have reported 20-40% decrease in range per tank!!!!), thus costing substantially more for consumer, even if they pay less at the pump through government subsidies...

 

if timing can advance a lot because of the anti-knock properties, then you can have a lot more crank duration at high piston pressures. It's very non-linear and one of the reasons that lower octane gas gets worse gas mileage dispite the fact it may have higher energy denstity.

Matt

 

According to OBC, I was getting 38+ mpg going about 62 the other night. That was the best I've seen on the highway.

03 MCS

 

unless you've checked it against the odometer using old fasioned math. Mine has been wayyyyyy off.

Matt

 

Matt keeps saying don't trust your OBC, yet people still do...I know mine is usually 3-5 off. My OBC says I get 21.5-22mpg, but my actual recordings are between 16-20mpg, depending on my driving. My average is usually 18mpg. I normally drive 190-200 miles between fill ups.

-Cody

 

I find following a bus or a big truck at 70 MPH really improves my MPG.
I don't crawl up it's butt, but just where I can still see the vehicle's mirrors makes a huge difference. I get up to 55 MPG in some situations on flat ground.