I had my MY03 for 3 months now, it's been great. Here is my concern:

Usually, I get 320km per tank before fuel light comes on (fuel consumption rate approximately = 11 or 12L /100km). I shift around 4500 to 5000 rpm and redline at least 2 twice a day. Recently had another encounter with a friend of mine who also drove the S...
He claimed that he could get 370km before the light comes on, yet he shifts at 3000rpm on daily driving, but vtec alot too.

Having this milage difference, I have decided to start and try to shift at 3k rpm and see what happens. I refueled my car last night to the top and had driven 3 to 4 short trips which makes total of 22 km. Low and behold when I started my car an hour ago, I saw two bars gone on the fuel gauge (which was all full before). Having seen this I went to the gas station and fuel up, and to top up the tank it took 5.23 Liters, which makes the milage to 23.67 L/100km (that means with a full tank I would only go around 200km before the fuel light comes on) I didn't vtec during this 22 km.

Would this be because I had too many short local trips? Or was it my break-in process wasn't done properly and is now hurting the milage?

 

I wouldn't worry too much about it. For all you know, the second time you filled up, the pump packed an extra liter of gas into the tank before the automatic shutoff. The only way to really track mileage is with a long term average, where the top-off errors average out.

And remember, it's not just RPM that affects fuel consumption, it's also throttle position. You can shift at 3k all day, but if you hold the throttle at 75% when accelerating, you'll burn more fuel than someone who uses 40% throttle.

 

I wouldn't worry too much about it. It doesn't sound totally off base. Like jeffbrig said, the top off error would really big with only 5 L of fuel. I find that using full tank fills good enough for estimating gas mileage.

Also, since the car is only 3 months old the engine is still breaking in. I found that 10k+ km the engine got noticably stronger. So my gas mileage got better since I don't have to push the car as hard to get my normal acceleration. My fuel consumption dropped about 0.5 L / 100 km.

Here are my typical fuel consumption numbers I've measured. Of course, it really depends how you drive.

City driving top down : 10 to 11 L / 100 km
All mountain roads top down : 9 to 10 L / 100 km
All highway top down : 8.5 to 9.5 L / 100 km
All highway top up : 7.5 to 8.5 L / 100 km

 

i'm the "friend" that mannn was referring to, here are my #s...(each tank was using Shell's 91 octane) yes ever since i picked up my S on Aug. 29 .. i've been driving a lot ... for the month of Sept. I drive to work daily (401 area to Bay+Dundas) in terms of hwy. / city. driving proportionally i think its about 1/2 .. if not a little bit more city driving thanks to T.O.'s bumper to bumper traffic.

Each tank of gas, I VTEC (7k+ rpm) probably 8 times or so (twice a day).

Mannnn: To ease your mind, these days is pretty cold and I'm barely reaching 180km @ the 1/2 tank mark... so I probably won't make it more than 370km for this tank of gas...

Date Litres Distance Cost Unit Cost Consumption
Aug-30 37.951 379.4 34.12 89.9 10
Sep-01 32.231 323.6 28.01 86.9 9.96
Sep-03 39.603 390.5 35.6 89.9 10.14
Sep-07 37.396 373.4 32.5 86.9 10.01
Sep-09 21.974 226.2 18 81.9 9.71
Sep-12 18.617 178.4 15.25 81.9 10.44
Sep-13 34.153 373.7 29 84.9 9.14
Sep-17 21.204 368.3 18 84.9
Sep-19 28.246 67.5 22 77.9
49.45 435.8 11.35
Sep-22 30.748 282.6 23.65 76.9 10.88
Sep-26 38.513 379.3 30 77.9 10.15
Sep-28 37.248 379.3 31.25 83.9 9.82
Sep-29 31.682 320.6 25 78.9 9.88
Oct-04 37.245 371.3 31.25 83.9 10.03

 

You have to drive thru the most of the tank to be get an accurate mpg reading.
You get worst mpg in the first half of the tank and better the bottom due to the difference in weight also.

 

here is mine..

 

FFS, too many god damned numbers! I have ADHD!