Strange phenomenon in my swift

[vikram_d]

Hey guys,

I recently undertook a drive to Chennai for business reasons. I noticed a very strange thing about my mileage on this trip. While driving down to Chennai I maintained a cruising speed of about 80 - 100 kmph and the mileage I got was 16.2kmpl. On my return trip I maintained about 110 - 130 kmph and the mileage I got was 17.5 kmpl.

1. Both the times the tank was topped beyond the auto stop of the fuel pump. I filled it up all the way up to the brim till I could see the petrol reach almost the top of the filler tube. So fuelling can't be different.
2. The fuel used was also the same BP Speed which is what I always use. So difference in fuel is out of the question.
3. Logically I should have got more mileage on my way to Chennai as I was driving from a city on higher altitude to a city at sea level. That means kind of an downhill drive. Where as it will be reverse on my way from Chennai to Bangalore.
4. I started from both the cities at almost the same time. I left from Bangalore at about 7:00 in the morning and returned next day. Started from Chennai also at about 7:00 in the morning.
5. The petrol bunk I use in Bangalore is also a reliable one (it is company owned) so I ruled out adulterated fuel.

So what could this difference in this mileage be attributed to? The thing that surprised me most was that I got better mileage when I drove faster. Any body have any similar experiences?

thanks & regards
Vikram

[theMAG]

Could your calculator have broken on the forward trip? And on the reverse trip?

What abt tyre pressures?

[condor]

That was two separate fillings - one at BLR, one at Chennai. That's one difference.

Next trip, you could try doing BLR-Chennai at 110-130, and Chennai-BLR at 80-100.

Is the mileage for the petrol filled at BLR par for that bunk? Quality of fuel at the same bunk can occasionaly change due to factors at production stage also.

[vikram_d]

Nope the calculator was not broken :-). Tyre pressure s also the same as i have nitrogen in my cars tyres. Any ways also did check tyre pressure to make sure about that, but was absolutely the same.

[vikram_d]

Originally Posted by condor

That was two separate fillings - one at BLR, one at Chennai. That's one difference.

Next trip, you could try doing BLR-Chennai at 110-130, and Chennai-BLR at 80-100.

Is the mileage for the petrol filled at BLR par for that bunk? Quality of fuel at the same bunk can occasionaly change due to factors at production stage also.

Yes the mileage is on par for that bunk as it is the only one i use always. Am planning to do what you have suggested on my next trip.

[madan80]

well, there can be several reasons for different mileage! most imporatly, when did you fill the fuel. if it is colder, you would have got a higher density, and hence a greater weight, so since bangalore is colder than chennai, that could have attributed to a few extra kilos. Also, when driving to Chennai, was traffic more stop and go? as in constant acc, steady state and then deceleration?

[vikram_d]

Well traffic was pretty much the same. Was able to comfortably maintain both the speed ranges without any problems. As far density is concerned, i dont think that it could have caused this difference.

[v1p3r]

Getting into Chennai is slower than Bangalore. Not that Bangalore is any great shakes, but having two roads, OMR and Hosur Rd, as opposed to only one (AFAIK) to enter Chennai, is easier on the drive. That could be your reason.

You mentioned filling up to the brim. But do you know if it was empty in the first place? What if there was some adulterated petrol already inside?

[k36]

Was car loaded similarly (No of passengers, luggage)? How was the AC usage and how was the weather?

[viper]

Originally Posted by vikram_d

Hey guys,

The thing that surprised me most was that I got better mileage when I drove faster. Any body have any similar experiences?

thanks & regards
Vikram

Hi Vikram,

Most of the customers using Tri-Phase have reported an increase in FE after installing the same.

Viper

[heavy_foot]

What is the engine rpm for swift at 110-130 kmph in the 5th gear?? i remember one of us stating that maximum fuel efficiency is achived if we drive on a particular torque curve... which is different for each car/engine.

[mobike008]

If you have ruled out all possibilites already listed below, i can say your a lucky man.

You get to kick dirt and also get paid for it ( read good mileage). So why you worrying?

[nikkibike]

Recall the traffic conditions to and fro!! Was it normal both way?!! Or was it a bit more/less in one side than the other?!! This cud be a major reason!! Usage of clutch/brakes really counts in my experiance!!

What say?!

[sharathjeppu]

I have experienced the same with my swift as well. I wanted to write about it earlier to find out if anybody else had the same experience but never got to it. :-)

My observations were during my trips to Mysore and back. I used to drive at a sedate speed and used to get a certain mileage. I used to rip on the return journey and get a much better mileage. I found this quite strange as it was quite the opposite on my Wagon R.

I am sure there's some explanation to this.

[vikram_d]

Sorry folks for not using proper grammar since i'm using my phone to reply, but i am inclined towards agreeing with heavy foot. i think since the swift generates both its peak power & torque at very high rpm's it is giving better mileage at higher rpms.

@v1p3r - both my fills were done outside of both city limits after i crossed all the city chaos, which is my normal practice for long drives. I filled my first tank on hosur road after all the city traffic. then refuelled again at sriperumbudur with meter showing half a tank of gas. while leaving chennai refuelled again at the same bunk and tanked up again on the same bunk on hosur road. the objective of this was to see how much difference my ripping would make.

@k36 - i was the only person in tha car both ways an a/c usage was also the same. on any drive the only time i switch off the a/c is when i smoke which is a very heavily regimented number.

@viper - this is not the first time i have taken the vehicle on a long drive with the tri-phase. but the first time i have driven at two different speeds on the same journey. i normally maintain 80-100 on all my drives.

@mobike008 - i'm not worried but just this behaviour unusual from my 16 years of driving experience.

@ nikkibike - the traffic was the same. as i have mentioned earer was able to maintain both speeds without any effort.

@heavyfoot - the rpm was between 3200 - 3700 at that speed.