Recommended speeds for gear change for Honda City ZX

Hello everyone,

I have some doubts regarding the recommended speed for gear change for my Honda City ZX EXi bought last October 2008. The car has done around 2500kms and I recently availed of the 3rd free service after 6 months of use as per Honda's recommendation. In this, they changed the engine oil and put synthetic mobil to the engine, which is more expensive than the ordinary engine oil.

As per Honda's recommendation, the following are the gear change speeds.

1st to 2nd - 24kmph
2nd to 3rd - 40kmph
3rd to 4th - 64kmph
4th to 5th - 75kmph

Accordingly I have been driving as per above. Recently one friend told me that according to the above, mileage will be low. If I change from 1st to 2nd at 20, 2nd to 3rd at 30 and 3rd to 4th at 40kmph, then I will get better mileage. At the present moment, the car is giving around 8.5kmpl in city driving with AC on all the time. I am using the ordinary unleaded petrol. Now I am confused. Can you please tell me whether I am doing anything wrong? Please correct me if required and tell me the recommended speeds for gear change.

Thanks and Regards,
Abhijit Dutta

In my opinion...

Change to 2nd at 10/15, to 3rd at 20/25, to 4th at 35/40 & to 5th at 50/55.  On highway you may accelerate a little more in 3rd & 4th gears.

Take my advice - I have followed it to the letter of the recommendation.

These are the really BEST change points, and give the best FE while acceleration. The logic behind this is the shift points are based on peak torque - occuring at 2700 RPM for Honda City. To get to these shift points in the gear mentioned, you need to really floor the throttle. This arrangement reduces the pumping losses (the energy lost in sucking air into the cylinders through restricted air path in a nearly closed throttle), allows free air to the cylinders and thus reduces emissions (as they are always calculated as % of the total exhaust flow.).

Only care one should take is not opening throttle wider than needed. The 'needed' part here is ~3/4th of the throttle, and ~80% load (these are parameters the ECU monitors to decide how much fuel injection the car needs). To the layman at the steering, it is literally 3/4th the distance to the floor for the throttle pedal, and a healthy load indicated by the engine (it should not revv free, but race healthily to the speed desired).

About only problem in this scheme is it produces so much of acceleration (without the associated guilt of wasting fuel) that it is not practically manageable in crowded streets. But it does allow one to race out from the dead stop at a traffic signal, and see everyone else (who try to change early as Pankaj mentions above (No offence meant, Pankaj) in the rear mirror, slowly fading away. Don't get fixated on the ORVM, the next signal is not far at this rate!

These speed points are good for accelerating, but not so good for coasting. There the power output required is minimal, and you don't need to follow those change points for coasting. Maybe now Pankaj's suggestion makes sense (use those points for coasting) or simply change to neutral and coast away, and look with amusement at others burning fuel, yet unable to catch up with you. I do the extreme, which I don't advocate others to emulate unless they are sober and take responsibility for themselves - I coast after shifting to neutral and switch off the engine - 0 fuel consumption for quite some time! Then bump start and repeat the cycle!

Don't go beyond 60-65 in city traffic - you will invariably required to brake, killing FE. Try to avoid alternate speeding and braking - that kills FE. Also see consciously if you ride clutch or brake by habit - that not only kills FE but also the clutch plate / throw bearings and Brake shoes respectively. Don't race to a glowing RED traffic signal - hold back and coast slowly to it. try and avoid the right lane to relieve you from the pressure to keep up with traffic - These points will help you get over your 8.5 kmpl problem. Honda city should give you ~12 kmpl in city with AC easily, if you are careful.

Hope this clarifies.

Thank you for your reply Krishna. I think then I am correct in the gear change speeds (i.e. approx. 20, 40, 60...etc). I will keep your tips in mind.

Car mileage involves 2 things. Upshift and downshift of gears

Upshift is when you are switching from a lower gear to a higher one and downshift is when you are switching from a higher gear to a lower one. Fuel saving works on a few principles - 

1) use less of clutch

2) use lesser brakes

3) avoid changing gears too many times since it requires you to use a lot of clutch

4) avoid sudden braking and acceleration

All these principles can be used by slightly changing the way we drive, and change gears

I drive a honda city exi and I manage to get a fuel economy of 13-14 kms/litre in city by my driving technique

While upshift I change the gear at following speeds - 

2nd gear - 10 km/hr

3rd gear - 40 km/hr

4 gear - 60 km/hr

5th gear - 70-80 km/hr ( I put the 5th gear only when I see a clear road for next 2-3 kms, else I keep it in 4th)

while downshift, I try and keep my car in 3rd gear only unless the speed drops below 20 or goes above 60. That helps me keep minimal use of gears, clutch, brakes and a better fuel efficiency. Basic idea is to change gears are correct speeds while accelerating and use minimum gears when down-shifting. 

Hope this helps

Thanks

Rocky, What a rocking first post! Welcome to CW forums!!

Just curious - what are the FE figures you get routinely?