JDEP162

last few tanks ive been keeping track of, just for the hell of it. havent changed the way i drive at all, i still romp and wot when i feel like it, including full passes on spray, and over the course of 4 tanks ive averaged 21 mpg.
mix of city, cruise country roads, track.
lid lm2 and spray. auto w 3.23 rear

FirstYrLS1Z

iTrader: (4)

MPH affects MPG.
Referring back to my posts #3 & #15 of this thread,on some of my trips to Florida,I purposely dropped MPH down to see what effect on MPG.
My 3.23s' base of 24.5mpg was with keeping with traffic(typically 5mph above posted speed limit). Doing a trip at posted speed limit gave me 25.5. Purposely driving at 5mph below posted limit gave me 26.5. Once on a trip to Michigan with the 4.56s' late night/very early morning no traffic on the Ohio Turnpike travelling at minimum posted speed(I think it was 40),I netted 28mpg with 4.56s'. Passing troopers didn't bother me because of my slow speed because there was no traffic I was impeding.

Ortadragoon

Mine is a 99 with a T56 and the economy is all over the place. My first tank was 19. Next tank was almost 24. Past two tanks have been somewhere between 21 and 23.

The car runs good. 135,000 (I've done 2000 of those) but the previous owner removed the cats so it's throwing several codes all emissions related. Im thinking that's a part of my gas mileage issues. I'm fixing to change the plugs and wires so hopefully that'll help, too. Car was taken care of but considering the owner before the previous was an older woman she did maintenance on a "if it's messing up fix it, otherwise forget it" basis. So I've got a lot of regular maintenance to do.

Always2Slow

iTrader: (8)

There are many many factors that go into what mileage your going to get. I have logged many highway trips with EFI Live and enabled lean cruise on my car. Getting timing right in your cruise cells helps in getting better gas mileage. Lower rolling resistance tires or lighter tires especially on the front end help as well. Overall weight, gearing, and mods will determine the efficiency of your motor. A few suggestions is to do a ram air type setup or even the free ram air mod and run a quality paper air filter. Cool clean air is your friend for starters. Make sure your O2 sensors are healthy and only run Denso 02 sensors. If you could get someone to tune your car your mileage will go up. To put things in perspective for you with a full bolt-ons motor with e10 I typically get 24mpg in mixed driving. With E10 275 summer tires on all 4 corners I can get 26mpg at 80mph. The highways i travel are relatively flat and help with gas mileage. I have filled up with real 93 gas before and my mileage was ridiculous I calculated 31mpg on that trip but was only driving 55mph on cruise control. I fill up my tank the same way everytime, so I feel the results are within .5mpg. Your car needs to be in a good condition overall to achieve good results.

Carguy8888

iTrader: (1)

What a great thread. I thought I had the exact same situation as the op. Now I know 16 to 20 MPG is a realistic number.

jmettee

As the OP, I wanted to update this thread. Since my original post, I've cleaned the EGR valve & PCV valve & replaced pre-cat O2 sensors since they seemed a little sluggish & I got a decent price on the new Densos. This past week, I had training for work & my commute doubled so that I used a full tank in 3 days. I had increased tire pressure from 32 to 34 PSI. With very little traffic & a lot of interstate travel ranging 50-70 mph, the best in the recent tanks of fuel I've gotten is 22.1 MPG.

Curiously, the ECU scan tool I have would report that my average MPG should have been 25-27 MPG. I'm going to just conclude that my particular car is not as good at getting MPG like some people do. The only other thing I think could be 'off' is the MAF sensor is reading slightly wrong, but I'm not going to the expense to change that out 'just for fun'.

DANOZ28

iTrader: (1)

sounds like you've covered all bases , i'd still change plug wires if stock (i like crane firewire) and at least get a street friendly mail order tune since gas milage is a priority. just my one cent , goodluck!