I've been cruise controlling my car on the highway and no more than 4 mph higher than the speed limit for two reasons. One I'm tired of getting pulled over, and two I don't feel like buying a new car.

 

As someone else stated in an older thread.

If you're worried about gas mileage, you SHOULD HAVE bought a PRIUS!

 

Any engine mod that increases the torque in the range that you operate, 2-3k rpm, will improve your milage. Torque is a measure of the efficiancy of cylnder filling. This means less throttle for the same performance.
From my searches I think that there is evidence that a 5/16" plenum spacer does give a modest increase in the rpm range that I drive in. My plan is to install one when the weather warms up. The only problem with this type of mod is that I will develop a heaveier foot.

 

OP, I think we're on the same page. I'm not "worried" about gas mileage, but I do want the engine to operate as efficiently as it was designed. I just bought my 03 a few weeks ago and averaged 19.5mpg on the first 3 tanks and that's after a new K&N air filter and a MAF cleaning.

But since you're high mileage like me (I'm at 109K), I'll emphasize checking the spark plugs. Just changed mine this weekend and they were definitely the originals. Gap looked nearly double vs the new ones. Went with the NGK iridiums since the price diff from NGK plats was nominal. Not through the first full tank yet with the new plugs, but I can already tell that I'm going to get more miles at the checkpoints on the gauge. I'm estimating an extra 2 to 3 mpg at this point. I've been running BP 93 the whole time, so that's a constant.

 

Did you change them yourself? If so, how long did it take you?

 

Yes, about an hour. Could probably do 30-45 min next time. Basically, just take off everything that's in the way (engine cover, air tube from airbox to TB, and most of the hold downs for the wiring harnesses on both sides). And be careful getting old plugs out of aluminum heads. Work them back and forth a little bit if they seem stuck. This is a good write-up, too. https://g35driver.com/forums/engine-...ug-change.html

 

lose weight. get a coupe midpipe and take out the spare tire and jack

 

You're not gonna really get much better fuel economy with they style of driving that you do.

My HWY mileage went from 23.5 on average to about 27.5 MPG from doing lots of mods but is basically the same around town.

 

High compression is good for efficiency. The Prius has a 13.0:1 comp ratio.

Not sure where you are getting your resale stats. The 2010 Prius is on the 2010 top 10 list for predicted resale value after three years (62%), but so is the Ford Mustang GT. Unfortunately I don't have the resale value for the 2010 G, but the Acura TL has a predicted resale after three years of 59%. I'm sure fuel consumption has an effect on resale value, but there is so much more to it.

http://www.cars.com/go/alg/index.jsp...RIUS&year=2010

 

Dude, you sound like me. I'm a total engiNERD. But listen to this guy, OP. I was thinking this same thing when I purchased my 5/16" spacer. I'm installing it this week, and I'm expecting to see some pretty visible results.

 

maintenance of everything would be good like others have stated. obviously driving is the number one, but cleaning and changing fluids will help also. It has not really been talked about on this forum , but meth injection could help and would be a fun project. With an added good tune maybe you get get a couple more mpgs. The G has no really simple solution for better gas minus how you drive, but I don't think anyone bought this car for grandma driving . Anyways goodluck!

 

You could drive like a complete old lady (and 100% miss out on what the G is really about) and maybe gain 2-3 mpg.

But at that point, you left your ***** at home and might as well buy a prius. Why be a poser? haha

 

Well, thanks everyone for the excellent comments and suggestions. Based on your advice, I think I have an idea of some of my next actions:

1) Not buy a Prius
2) Change/upgrade my spark plugs
3) Check/replace my air filter - possibly with K&N
4) Change my oil with Mobile 1 High Mileage full synthetic and a K&N oil filter
5) Check my tire pressure
6) Clean my MAF
7) Get air/fuel ratio tuned
8) Take granny driving lessons

I'll post back on here as I make these changes and see how they help.

I'm already using my cruise control and am pretty light on excess weight. Someone suggested taking out the spare and the jack, but that doesn't sound like a good idea for anything other than saving gas. I do have the full-sized spare, so it would save a few pounds though.

I will also keep my eyes open for a Z-Tube and/or 5/16" plenum spacer at a good price, but I don't expect these to have much of a positive effect on my mpg. I'll look for a K&N air filter too.

I may also try different brands/grades of gas. I've read that different oil companies' blends have more/less btus due to the grade of crude they start with. Does anyone know if there is a website that tracks this info?

 

The z-tube to me is a very good upgrade. i was averaging 300/tank. after the z-tube i began to average 380 and was very suprised. plus the added satisfaction of how your engine sounds. and a few hp just because. K&N is my next upgrade and coming up on 60,000 so changing plugs also . Driving a 2005 6mt sedan. is 6mt better or worse for mpg?

 

[you do not say if your car is auto or 6mt. I found that a lot of my driving was around town which was too slow to use 6th gear and found I was driving alot in 5th gear sometimes because I forgot and found that I was then driving on the open road even at speeds of 50mph. I am now more conscious of my gears and get into 6 th as soon as I exceed 45mph. also take note of your tires size. going to as size l/2 taller will increase your gas mileage 2 percent. example say your tires now need replacing and they measure 215-70-17 just move up to the next size such as 225-70-17