the sweet spot is actually within the power band...between peak torque and peak power....say 4k to 7k... but we don't usually try to do century run ah from every traffic lights... hahaha

so the comfortable gear change ends up just before or around the peak torque rpm... old engine around 4-5k, modern around 3-4k... except rotary around 7-9k...

I enjoy driving...so I don't worry about fc... but since I know the "secret to good fc" , my fast launching and higher speed don't sap my fc too much... hahaha

Fast launch and higher speed dont sap my fc much

Tbh, fuel consumption not much difference between speed. Lets say someone cruise 80kmh with someone cruise 100kmh.

The main culprit is acceleration. that is why cannot launch fast fast. Yeah, I met a lot people like u, fast launch then long driver hope the fc will be efficient. its not.

if u got fc reading on dashboard, u try drive
1) 2k rpm, then cruise 100kmh
2) 4krpm, then cruise 80kmh.

I had try above method and Option 1 is more fuel efficient. But option 1 cannot be follow by someone who easily butthurt at traffic light and want to win drag race like what 90% malaysian driver are.

I dunno why, the option 2 just dont work. Maybe too much fuel burning during that short period of times.
No need to glance so frequently la bro..sometimes also can..the most important is rights leg is consistent.

you're complicating the issue.... constant 140 will use more gas than constant 100... for sure

and erratic driving style will hurt fc...as you know

Not far dude..100 can be as high as 140 if rough driving which is habit for malaysian.

not really, during mco I hit 5.5km/L on my car, that's without any other car on the street, I jam 20 years also never hit that level of FC.

My idea it save fuel for bigger engine where even on 140kmh, rpm stay below 3k rpm

But if it a Viva Elite, at 140kmh the rpm hovering at 4.5k then it drink fuel a lot

let's just say i miss those mco days

before this I also believe, rush hour traffic jam stop and go crawling it's what destroy the fuel consumption,
but after 2 months of mco with me still going to work using the same route with 0 traffic, end up using more fuel

so I don't know what to believe now

Here's spreadsheet I developed to compare transmission of various car type at redline and 3000rpm. It shows their theoretical top speed if not limited by engine power or electronic.

More powerful engine can afford to have wider overdrive gear ratio thus cruise at lower rpm, it is the transmission.

Gearbox change speed and torque. A 10 to 1 (10:1) speed reduction gear set reduce the speed from driver to driven gear by 10x, it also amplify the torque by 10x. In overdrive, it is the other way round 1:2 ratio double the output speed, but drop the torque by half.