05 9-5 Aero poor fuel economy.

Okay so this has been an ongoing issue, I have a 05 Saab 9-5 with 2.3 turbo 4 cylinder and I.m averaging 15 mpg with mostly city and some highway. I can not mentally comprehend how an engine this small can consume so much fuel especially because i never bring the engine over 2500 rpm unless I want to have some fun. So far I have changed vacuum lines, plugs, fuel filter, cleaned maf/throttle body, and I only use premium. I've used a couple of fuel additives just for poop and laughter but they made no noticeable difference. Looking for any suggestions.

check your plugs if they are sooted or lean changing them could do a small difference
Basics First -
Check all vac lines for condition - even a dry rotted line can cause issues (Replace as many as you can)
Replace any suspicious parts - like your By Pass Control Valve (Hooter Valve)
New correct Spark Plugs
New Fuel Filter
Clean Throttle Body
Clean Air Filter
Tire Pressure - 36 all (I tend to run 38 front and 36 rear)
Fresh Trans Fluid! A simple Drain and Fill Will improve performance.

Disconnect the battery for a few minutes and reconnect to perform Swedish Tune Up

Do you ever clear your SID when you get gas? It's a good habbit to do this every few tanks of gas - otherwise your SID MPG will be way off and it will effect your DTE value.original post from Burnside

I've done all of that except changing or cleaning the bpc valve. I got a tranny flush this summer and did not notice any difference. Im thinking perhaps an exhaust or DIC related problem just because i have rules a lot of other things out

from my experience if you are replacing the DIC make sure to get OEM original equipment manufacturers. I have bought aftermarket DIC and believe me there is a difference. The OEM is well worth the extra money. Good luck with your car and I hope you figure out what is going on with it.

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+1 on this :thumbsup:

I had a MPG issue on my 2002 9-5 Aero. I went through the same things swisssaabist mentioned. However, my issue was that the throttle body gasket was half gone. Whomever put it on last put it on very incorrectly. Might be a throttle body gasket issue.

it could be too

Fuel pumps become inefficient over time as well, have you changed yours yet?

If not, you're in luck, you have the best year of that generation Aero, which means you don't have to drop your tank to access the pump!

You can snag a new assembly one on EEuro for about 130, and it comes with a new pump too!

I don't see on your list:

New DIC
Fuel injector maintenance
Fuel pressure regulator (might be crap in there, but unlikely)

Literally plug and play, just be careful when you remove the send and return lines so you don't cause a boo-boo!

My money's on the pump, @Digger - what's your take on this?

If you need info/links, let us know and we can get you sorted.