Wira 1.5(M) 3.8K RPM for 110km/h ..

My Gen2 campro engine also same.. consume petrol so much when RPM over 3k. 

You are wrong. It will not change. Your speedo comes from your gearbox. It is fixed. Changing the size of the wheel will not change the readings on your speedo meter. It does not matter whether you change to 20inch. If the rpm is 3000rpm at 110km/h on the respective tacho and speedo meter, it will remain at 3000rpm at 110km/h even if you change it to 20inch (even though you are travelling at 130km/h).

You have to remember that there are always 2 speeds.

1. KM/H on speedo meter (this cannot change as it is a fixed reading from the gearbox)
2. KM/H actual speed (this will change depending on the OD of your wheel)

What we are talking here is the reading on the speedo and tacho meter. Actual speed aka real speed aka speed captured by speed camera will change but not the reading on the speedo and tacho.

sleepwalker: can you explain a bit what is "clutch is slipping" ? Clutch want finish already, no teeth ?

i wanna ask.. i driving Kancil 850 Auto, RPM is maintain 3k when i was on 80km/h, is count normal or got problem? full tank RM60, can only go for 200+ km, count as normal??

I feels that there is no difference in term of FC while cruising at 110km/h and 14km/h. Several CPS user also confirmed this. 
Correct. Only the actual speed will change when changing rims size. Can try to googled cars bible and use the provieded calculator to see how much the difference.

your car engine 850cc only mah. cant get high speeds. at high speeds, u pushing the engine too far and this means higher fuel consumption

my old iswara was about 3.1k @ 110km/h.

I using campro
I also tried before...if i run over 130-160kmh (RPM stick at 3.5-4k). Only can run over 480KM per tank.
If drive slow slow 90KMH (RPM only 2.5-2.7k). I can run over 550KM per tank.

oh.. that means is normal de la? cause really feel like high fuel comsumption =.= i thought kancil should be save fuel de ma =.=

I feels that there is no difference in term of FC while cruising at 110km/h and 14km/h. Several CPS user also confirmed this. 
Correct. Only the actual speed will change when changing rims size. Can try to googled cars bible and use the provieded calculator to see how much the difference.

For most cars, max efficiency is gain around 90-100km/h where the best rpm to speed ratio is gain and wind resistance is not an issue. Any slower and the rpm to speed ratio is no longer efficient as you take longer to reach your destination and any higher speed would encounter wind resistance that will require more fuel to keep the car running at that speed.

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Added on August 1, 2008, 9:44 am
Wrong. Rusty nail is correct. Your RPM per KM/H on your dashboard will still remain the same. The only thing that will change is your actual speed and not speedo speed, meaning if the police shoots the laser camera at you, then you will be driving at 120km/h but speed still show 110km/h. That is how bigger wheel OD will affect you. It will not affect your speedo but affects your actual speed.

The common fuel efficiency gauge is on 90km/h at RPM 2k. That's the myth.

The common fuel efficiency gauge is on 90km/h at RPM 2k. That's the myth.

haha i think for high capacity engines, its possible to have lower rpms.

for a 3.0L accord or bmw, i think the revs is around 2.5k or lower.