fuel econemy

[hdtkid]

hi guys,

maybe a few of you can help me with a bit of a econemy isue my sister is having ...

my sister has a VZ wagon auto aloytech 3.6 with aprox 170,000ks, i have a VS sedan manual ecotech 3.8. aprox 450,000ks and my car gets far better econemy than my sisters, dispite the bigger engine. from sydney to parkes and back my Vs can do it on 53lt of fuel with the aircon on just about all the way. my sisters car uses about 80--85lt thats a big diffrence that can't be blamed on driving style or a manual vs auto transmission. but everything about my car says mine should use more fuel. its got big fat wheels 235/40/18 my sister is running stockies 205/65/15(i think), mine is manual so i can drive it hard (with in the laws and do so constantly) extractors, dyno tune, bigger throttle body and injectors, list goes on... any idea why mine is far better on fuel????

we both use 98 fuel either shell or caltex depends who is cheaper, and when i did the run were i checked exactly how much fuel i was using i also had a fully loaded car. 3 adults and every inch of free space had something in it.

if anyone has some idea as to why this is or things i could check on my sisters car im sure she would be thankfull
both cars are well looked after and have regula wheel alighments tyre presures are always checked before long runs.

only thing i can think of is the areo drag caused by the wagon, but if anyone has some ideas i will pass them on to my sister and see if it helps her.

PLEASE NO FIGHTS everyone im sure has diffrent opinions. im just trying to get to the bottom of why mine is about 40% more eficent.

 

[Towcar]

My Dad told me to stay away from the 3.6 as they were thirstier than the 3.8 as the 3.6 revs higher to make its power, but that sounds excessive.

You have had a tune, which would make your car more economical, as usually when you tune for performance you lean out the mixture.

The wagon is a long wheel base, where as the sedan is the short wheel base, I imagine making it lighter.

So from Sydney to parks google says 360km, but for all I know you could live either side of Sydney! you get 7.35l/100km and she gets 11.1/100km seems your car is running really well, and your sisters is a little thirsty. I am sure my VX would be between the 2 but that is a V8.

 

[Pollushon]

So you're getting 7.5L per hundred on an Emo, and she's getting 12L per hundred on an Alloy? You have an exceptional 3.8 and something is wrong with her VZ. Best I could do, pre and post boost is 10L per hundred. That's about average for a maintained Emo. My mates VZ sedan does 8.5L per hundred, a wagons aerodynamics won't affect things that much.

She should look at things like O2 sensors, leads and plugs, maybe take it in to a mechanic to run the oscilloscope over it.

 

[commodore665]

What speed does she drive at ?? , the wagon would be a bit heavier , interesting to see your mods , I had on my VX , bored out throttle body ,with tune , extractors , exhaust , CAI , plenum, and manifold spacers , roller rockers , and my VZ SV6 is not only more powerful , is more economical on fuel , she may want check things like plugs , filters , even a service , as in oil change might help , I doubt wether the fuel you are both running would influence the economy , mind you when I used to run Caltex 95 in the VX it ran a bit shite .

 

[Cava454]

VZ SS ute. Head and cam 300rwkw, 6 spd, 3.9. Driving too and from the city.

The dash tells me 12-14. Bowser says 16-18.

 

[ari666]

7.5/100 is mind blowing

 

[hdtkid]

thanks for the input guys.. sisters car is well kept, so something just dont sound right maybe she needs a better mechanic lol
ill pass on this info to her and get another mechanic to look over it asap.

her o2 sensors were done recently, oil gets done every 5,000. plugs and leads im not sure ill have to ask her,

if anything i drive faster than her and probably with more lets call it "enthusiasm" lol so again im suprised hers uses more. if i went on an econemy drive would be intresting to see what numbers i got with mine.