New guy here with a Subaru!

[Ilikebmx999]

Hello everyone!
I've been looking into ways to improve mpg's on my 04 Subaru Wrx wagon. Driving style alone nets me an average of 28mpg but I like to improve on that. Anyways I look forward to learning from everyone!

Is there a good FAQ or best place to start to learn about getting better fuel mileage?

Joel

[theholycow]

Welcome.

There's definitely plenty of reading around here, but maybe we can help you zero in on some ways to improve.

What are your priorities? Do you want to save fuel mainly to save money, or are you willing to spend money to save more fuel for the sake of the environment (or limited fuel supply, etc)?

Is your car manual or automatic?

To start with, running high tire pressure (like autocross contestants do) can often improve a car's fuel economy. It's often my first suggestion because it's so easy and free or cheap. You should never inflate less than the car's recommended pressure nor more than the tire's maximum. Experiment in between to find out if handling and/or comfort are compromised. In my cars I always get up to the tire's maximum pressure before comfort is compromised, and handling has only ever suffered on the rear of my pickup at 80psi.

Often, those with manual transmissions can save fuel by opening the throttle more and shifting lower during acceleration, accelerating at the same speed as normal but at lower RPM and wider throttle. That may not be effective on your turbo car, which may spool at low RPM if you open it up like that.

You should put your car in The Garage on this site and start logging your fuel usage there. That will help you identify what works.

[Ilikebmx999]

Well I guess I could elaborate on my car and driving style more.

I use my car for daily commuting and fun. I put an average of 350 miles on it each week. I'm looking for fuel savings for money reasons mainly. I'm looking for a balance of performance and fuel economy. My car is also modified a bit and I have tuning software so I can also make changes in my ecu for enhanced improvements.
Driving style:
I'm very light footed and generally shift around 2,500 rpms. I also keep my tires inflated at 38psi. I've thought of going higher but am worried about uneven tire wear.

About my car:
04 Subaru Wrx wagon
85k miles
5 speed manual
2.0L engine
full 3" turbo back exhaust
catless uppipe
ecu tuning
ported tgv's (portion of intake manifold; very restrictive)

[Ilikebmx999]

Oh I forgot I'm willing to spend money to be more efficient assuming it's not crazy expensive.

[theholycow]

Money spent to be more efficient rarely pays for itself.

Your tuning software may be able to help. You probably won't want to give up low RPM boost for when you're in a hurry, but does your car have a switch for performance/economy mode and you can program it to spool only at high RPM in economy mode?

Either way, you may be able to program it for more aggressive DFCO (Deceleration Fuel Cut Off). That will be a small improvement, for free.

Before any programming, if you're not sure you should definitely check with a Subaru tuning forum to see if it will damage anything. It can be difficult to ask if they think you might be sacrificing some performance for fuel economy, as those types of forums often tend to be close-minded about the issue.

What road and traffic conditions do you drive in?

[Ilikebmx999]

Basically on the Subaru forums everyones response was "why'd you buy a Wrx if you're concerned with mpg?". I feel like I could get both peformance and better mpgs. I'm already above EPA standards but I feel like more can be done.

Even on only wastegate pressure I can see boost at as low as 30% throttle. Full spool is at 2800rpms. I'm very rarely in boost daily driving however.

My driving conditions are normally
25% on 35mph roads with stoplights.
50% rural roads with a speed limit of between 45-55mph
25% highway with a speed limit of 55mph

recently my highway portion has been hit with major traffic due to construction so I've been taking another route that replaces the highway portion with more 35mph roads with stoplights. It's a little shorter in distance and time wise I save about 20 minutes. Certain spots of my commute do see congestion because of the normal rush hour traffic.

I think working on some aero mods and maybe a bit of tuning would be my best solution. Are simple things like taping panel seams and blocking front airflow that effective?

[Ford Man]

Originally Posted by Ilikebmx999

I also keep my tires inflated at 38psi. I've thought of going higher but am worried about uneven tire wear.

I'm running 50 PSI on my '97 Escort and haven't noticed any abnormal wear.

[Ilikebmx999]

My car weighs in at about 3000lbs and My tires have a treadwear rating of 240. I assumed with those two combined with high pressure would give me poor wear. Guess I'm mistaken

[Ilikebmx999]

Looks like I'm not the only Wrx wagon on here. I found this person....and all I can say is I'm doing much better then them already!

http://www.gassavers.org/garage/view/1516

[Ilikebmx999]

Here's a picture of my wagon....I feel like a decent amount could be done to make it more aero!