They did over at that huge my350z thread about the UpRev Osiris. But I read that along time ago.

From what I remember with the conversation from Shawn Church, the car runs a little leaner and timing is pulled a little (iirc). The ECU also prevents you from going 100% woot (iirc).

I might have to check back with Shawn.

 

I pulled my timing back about 2 degrees... oddly, I'm making my best power with less timing too. It might be the slight difference in octane (91 max here)
But before the tune, my motor was running really lean with all the mods I have, so I did the most sensible thing to do... add fuel.

 

I sploodged the "mod bug" out all on my Z. I'm pretty much done with the go faster part, I honestly was just thinking it would be nice to be able to achieve 25mpg with conservative driving.

 

So what is your cruising speed to achieve 30 mpg? I've heard something like every 10 mph adds almost twice the wind resistance to overcome.

My problem is keeping it below 75 so I'm hoping you don't say 55!

 

I drive 70 with cruise control on. Anything over 75 is all bad for fuel economy on my car...

 

Hey guys,

Newb here with an 05 Lakeshore Sedan Sport 5AT. I've had my car 2 weeks and so far I average 18.5 MPG in mostly city driving. Would a plenum spacer help with the mileage or just with power? I'm sure this question has been asked already, but I've got to run to work so no time to search.

I really love this site; lots of good info, good people, and a couple of hotties to boot. Good lookin' out!!

 

maybe tires? get one with less rolling resistance.. inflate to 35~36 psi.
Quality of gas should matter too.. try to use "brand" name premium..

I usually get ~23 in the city. 30+ on the freeway probably going ~65mph most of the time... (fully stock).. maybe winter gas gives you worse mileage..
i could of sworn i used to get 26.5mpg mixed driving in the summer..
but i've been getting 24mpg recently in the winter (snow tires on also)

oh yea.. try not to use A/C or heater.. i rarely use them..

well.. this is in Denver.. when I was in California, i used to at 20mpg mixed.. but i sat in traffic on the 55/405 a lot..

 

I wouldn't suggest over filling the tires... it works, but you lose traction which wouldn't be a big deal for normal driving, but will be important if you need to make emergency maneuvers... I'm sure not getting wider tires can help too.

 

i thought it was only ac that used extra gas?

 

this is true, the heater does not use gas.

 

i wouldn't say 35~36 is "overfilling".. i would say on "emergency maneuvers" such as avoiding a pothole (lol), the 35 psi should help.. The max PSI on most OEM size tire is 51 PSI anyways.

 

how can heater not use ANY gas? something has to turn the blower right? I know that it's electric, but something has to create the energy.. in the end.. the alternator works harder.. and more gas will be used indirectly..

(don't quote me on this.. i am no engineer)

 

The highest MPG I've ever achieved was 29.7mpg (496 miles on 16.7 gallons). That was on a trip from Atlanta to St. Augustine, FL in 90 degree weather, flat grade, 65mph on cruise, two adults, one child, and a trunk with 120lbs+ of gear. In the Midwest, where it's far more hilly, far more windy, higher elevation, less traffic (means faster mph), I tend to see 24-26mpg. In pure city driving, I see 18 to 19mpg.


Thing to improve mpgs:

Steady, moderate throttle
Properly inflated tires
OEM 17s with 215/55 rubber (ie no larger rims, wider tires)
Sub 65mph highway cruise speeds
Don't carry excessive junk in the car
Don't run the A/C as much
Avoid city driving
Use premium fuel
Avoid short drives (sub 5 miles), especially in the winter
Ride a bike

 

Regarding AC and heater...

Heater - sorry but that's a bit silly to not use the heater because of the fan. That's like saying don't turn on the stereo because of the power usage. This is really splitting hairs here and if you are looking to save that tiny amount of fuel, drive a hybrid.

AC - there's an interesting theory that when driving on the freeway in hot weather, it's better to use the AC then to drive with the windows down. The theory is that you loose more fuel due to increased wind resistance with the windows down and then you gain with the AC off. Just a theory that was tried to be verified on myth busters.

Better to drive with a lift foot and enjoy the car.
That's my 2-bits and I'm an Engineer (but I don't own a G37 yet.....but hoping).

 

The one thing that goes through my mind when I saw that episode is that they used an SUV... the thing has no aerodynamics at all... wouldn't a more aerodynamic car that redirects air more efficiently be able to handle that little loss much better?