Fuel Consumption Decreased But Less Fuel Range?

[Crawf]

So on my VZ SV6 Auto I had my rear muffler removed and replaced with a straight through pipe. This was just to give the car a bit of sound, it has and i dont mind it. Since doing this my fuel consumption has dropped from around 11 or 12L per 100Km and 600km to a tank, to 9.5L per 100km and 500km to a tank. Why has this happened? It doesnt make much sense to me. Any input would be appreciated.

 

[ephect]

Ur average fuel gauge has to be wrong.

 

[m1lky]

Are you filling up earlier? Only way those two statements could be true.

Fill it up and reset trip odo. Then next time you get gas fill it up again.
Then work out your avg manually. Liters of fuel / km travelled x100

 

[Crawf]

Nah iv filled up twice since iv had the exhaust done, both times the tank was completely empty. I filled up fully and reset the computer both times, same result.

 

[tim005]

I would say it's because of your exhaust your giving it a bit more right foot because the new sound has you all excited, but that wouldn't explain why your average has dropped...

 

[Crawf]

Iv been told that by a mate as well lol, but i dont think it's that either because at 2500RPM it sounds the loudest so thats as far as i usually put the foot down.

 

[Benboy]

The only accurate way of calculating fuel consumption is to fill your tank to either first click-off or to the very top (until you cannot get another drop into it). Suggest that you try and fill from the same pump next time and ensure that you follow exactly the same filling routine (whichever you choose) to ensure some degree of consitency and accuracy.
You cannot rely on the instrumentaion of the vehicle for ACCURATE results.
Using the following formula:

Example a car uses 65 litres to travel 500km

(65 X 100) / 500 = 13
That's 65 (litres) multiplied by 100 then divided by 500 (kilometres travelled) = 13 litres per 100 km travelled.


The formula is:
(Litres used X 100) / km travelled = Litres per 100km.

Good luck.

 

[Crawf]

Thanks for that. Both times iv filled up it has been to the very top, as i live on a farm i fill up from our own petrol tank which has no click-off system or litre monitor, for this reason i can't monitor how many litres i put into the tank each time. But i do know both times i have filled up the tank has been pretty much completely empty and I have filled the tank to the very top.