[narayan]

i think the usage of AC brings down the City FE much more than the Highway FE.

meaning, in the Highway, % drop in FE with AC and without AC would be much smaller than in City

[Dr.AD]

Originally Posted by narayan

i think the usage of AC brings down the City FE much more than the Highway FE.

meaning, in the Highway, % drop in FE with AC and without AC would be much smaller than in City

Are you sure this is the case? I never drive without AC so I do not have any first-hand experience about this. But this seems a bit counter-intuitive.

The power consumed by AC compressor should be the same (for given outside temperature and given inside temperature) regardless of whether the car is being driven in city, on highway or it is just idling. So this is a constant load. Now, the actual load on engine (load of pulling the car) is much higher in city (because of frequent accelerations from low speeds and higher time spent in higher RPMs) than on highway (where most time is spent in cruising in low RPMS). Thus, compared to the total engine load, the percentage of AC load should be lower in city than on highways. Hence, it seems logical that not using AC should have comparatively smaller effect on FE in city than on highways.

One argument against the above logic could be this: The FE is not a linear function of load on the engine or the power extracted out of the engine. Thus, if the total load on engine goes beyond a certain point, then the efficiency decreases much more sharply. Therefore, in city, when the load on the engine is already high, adding the load of AC may results in a dramatic decrease in FE. On the highway, when the engine is in lightly loaded state, addition of the AC load (although higher in terms of percentage of total load) may still not push the engine beyond the point of dramatic decrease in FE.

What do you guys think? Does anybody have some data to elaborate on this?

Thanks,
-AD

[Gansan]

Originally Posted by narayan

i think the usage of AC brings down the City FE much more than the Highway FE.

meaning, in the Highway, % drop in FE with AC and without AC would be much smaller than in City

I agree. So far as I have observed, the drop in FE of my Alto in the highway with AC is just about 1 KMPL. It is > 2 KMPL in the city.

[nithesh]

Originally Posted by narayan

i think the usage of AC brings down the City FE much more than the Highway FE.

meaning, in the Highway, % drop in FE with AC and without AC would be much smaller than in City

I completely agree with this. There's a big drop in the FE of my OHC 1.5 AT in the city with AC. I get 7-8kmpl with AC in city(Mumbai traffic) and 14kmpl with AC on highways. Thats quite a big difference.

Cheers.

[dhanushs]

Wayanad - Bangalore - Ooty - Mysore - Wayanad

Total kms covered - 951
Total fuel consumed - 62.71 liters of petrol
Fuel Efficiency - 15.16Kms/Liter
Vehicle - 2007 Ford IKON Flair.
Odo Reading - 92***

The trip included about 150kms of Bangalore city driving, 80kms of ghat driving in just 1-2-3 gears. Highway runs at 80-130km/hr with moderate ripping.

At nearly 1L kms on the odo, my IKON is still going strong.

[jatinpatel]

All figures are condiering Mumbai driving conditions with AC on always

Maruti 800 E3:-12.5-13kmpl(city) 16kmpl(highway)
Honda Civic A/T:-6.5-7kmpl(city) highway not yet known
Mitsubishi Lancer:-7-8.9kmpl(city) 12-14kmpl(highway)

[Iamcarnovice]

Figures for Punto Active 1.2, in Chennai

Normal City driving: ~11 KMPL

Highways: 4 passengers 100% AC: 15-17 KMPL

[sushantr5]

Figures for Vista QJD with 52k on ODO.

I got mileage of 23.2 KMPL on all highway drive with consistent 80 kmph speed.

[hemanth.anand]

My November first week trip in my FIAT GRANDE PUNTO 1.2 EMOTION:

Bangalore -Mysore-Ooty-Mysore-Sakleshpur-Bangalore

The trip to ooty and back till mysore yielded 13.8kmpl
(Ghat section mostly 1-2-3 Gears)

The trip from Mysore to sakleshpur and back to bangalore yielded 15.6 kmpl. Mostly good and flat roads.

Start of the trip ODO 950kms
End of the trip ODO 2450kms

Going for the first service next week

[EasyR1der]

Just going a lil off here, Is the Avg Gauge is how you guys check your Fuel Efficiency or manually ?

[bhp_maniac]

Maruti Swift VDi - June 2010
Odo - 6100
FE Best - 21.7 (80% Highway - Speeds around 120 - A/C On 80%)
FE Worst - 15.4 (20% Highway - A/C On)
Mileage Average - 17.54 (40% City - 60% Highway - A/C On 70%)

[hemanth.anand]

Originally Posted by EasyR1der

Just going a lil off here, Is the Avg Gauge is how you guys check your Fuel Efficiency or manually ?

I calculated manually( full tank to full tank)
the guage readings were 13.1 kmpl and 14.7kmpl respectively

[OHCVtec]

Car: Stock OHC Vtec
Model: 2002
Mileage: 64,000
Max FE(Mumbai-Pune Expressway): 20 kmpl
Min: 13 kmpl

[supremeBaleno]

Originally Posted by Mr_Bean

Recent highway drive, chennai-bangalore-chennai
Speed - 80 km/hr with occasional burst to 120-130. AC - 100%
FE - 18.1 km/litre Car - Suzuki Baleno

Thats nice FE.
I have never managed more than 16kmpl highway FE on my Baleno - my speeds are 100 and above. Have always wanted to try out a highway trip @80kmph to know what is the best I can get - from your experience, 18 should be possible.

[speedKrazy]

Car Punto 90 HP

Mileage 5600kms

Highway with speeds 80-140 19.5kmpl
City - 14 to 15 kmpl