What did improve the fuel economy for you?

[instarx]

That's amazing to me. I keep hearing these kind of things from a few people with 98-00 V70 XC's. I can never seem to get mine much better than 25 with an all time high of 26.

I commonly get 30 on long highway trips and have gotten 31.8 several times, with an all-time high of 32.8 (but my end point on that trip was NYC, so I could not refill the tank myself - it may be inaccurate). I inflate my tires to 40 psi, use 0w40 synthetic oil, and keep weight to a minimum. On my last 350 mile trip I got 30.5 mpg at 69 mph (with cruise control and using the A/C). As always I determine the mileage by odometer and gas pump volume, not trip computer. I have a 750 mile trip coming up for Thanksgiving, I'll let you know how that goes.

[kurtio1965]

Some of these posts amaze and baffle me. I have 98 V70 in really good mechanical shape. I run synthetic blend, etc. My mechanic tells me to run nothing but Chevron gas..which I do. It was AWD but I had it disabled and removed. 2.5 turbo. The best I have ever managed is 22 mpg. I am going to try a K&N filter and also do what another "poster" mentioned...remove the resonator and install and MagnaFlow. Hell, it least it will sound cool!

[rmmagow]

My 98 V70 AWD w/160K miles gets a reliable 24.8 mpg all the time. 70 MPH tops, generally about 65 or so, 100 miles a day commute in mixed but mostly highway. I use mid-range gas, 89 octtane maybe? 91~93 once in a while. Regular dino oil, clean air filter and tranny stays in S. I do run tires high, about 34 front, near 40 rear.

[dan777]

I've seen a big difference after I used the Auto-RX (oil additive) for the first time in my 2000 V70R. After about 5-600 Km the average consumption (city 70%, Hwy 30%) dropped from 13.5 l/100km to 11.5 l/km (17MPG to 20 MPG). Using premium gas vs regular gas saves me about 1 l/100km (1.5MGP).
I've tried other things (2 oz of acetone per 10 gallons gas, K&N filter, higher tire pressure vs recommended, AC off) with no significant results. Usually I get 8.5 l/km (27.5MPG) on Hwy and 11.5 l/km (20MPG) combined.

[RDEJR]

Not trying to thread-jack, but I am a bit bent about how good everyone's fuel economy is compared to mine right now...

When I first got my GLT, I was achieving approximately 20MPG.

I've completed stage 0, and now it runs better overall with more response and more power. The only thing that sucks is I am still only getting 20MPG, if that, and on the freeway only it's 21MPG. I calculate based on odometer vs. gallons to full. I go to the same gas station, and its usually the same guy that fills my tank, and he's pretty accurate with it. I run 87 octane because 91 made no difference what-so-ever.

Engine only has 140K, fully tuned up, doesn't smoke, has plenty of power. I've modified the airbox for cold air only, I keep the tires fully inflated, and I drive with a light foot. In fact, I get crap all the time from my Fiancee about how I "putz" around instead of driving like a "normal" person.. LOL

I drive the speed limit, and I am generally not in a hurry to get there. I honestly can't think of anything else to get the MPG up on this thing, and it's driving me crazy.

I've sea-foamed the fuel system twice, and I plan to sea-foam the oil to get rid of a single lifter tick that I have when cold, and then sea-foam the combustion chambers, though I sincerely doubt it will make much difference in MPG. I generally do about 40/60 city/highway driving. Highway speeds are only 55 - 60mph.

The only CEL I have is for the PO410 Secondary Air System Malfunction, but I don't think that would affect how the engine is run; much less fuel economy. I can't fathom how anyone is getting better than 30, and it grinds my gears that I can't do the same.

What gives? Currently, my fuel gauge is reading smack between 12 and 18, which means its sitting at around 15 gallons, and I have 57 miles on the odometer since fill up, of which about 50 are highway at 55 - 60MPH.

Any thoughts?

[erikv11]

Do you know if the oxygen sensors or MAF have ever been changed? Especially the front O2 sensor, it can wear out and affect fuel economy without throwing a code.

Also consider some of the other things that can affect air:fuel mixture and cause the engine to run rich - Does your car warm up quickly to normal operating temps on the gauge (i.e. is the thermostat good)? Has the ECT ever been replaced?

Clogged cat or otherwise clogged exhaust?

It is so frustrating to just throw parts at an elusive problem like this, I am not proposing you do that. But maybe get set up with a good OBD tool and check out air mixtures and O2 sensor readings, for starters. I am not well versed in that area can't offer much more advice if you want to go that route ...

Or maybe that same guy at the same gas station, always dilutes the gas he dispenses the same way

[jblackburn]

I've never seen anything better than 23 mpg on the highway with 87. I just have to push the car too hard - power SUCKS with regular, while 89 runs just fine. Mine's a different motor, though - and T5's are much bigger gas hogs than NA's.

Do you live in a hilly or windy area? I can make the trip down to DC and average 29-30 mpg pushing 80 mph, but on the way back, doing 75 or so, I usually only get about 25.

The only other things I can think is either:
1) Vacuum leak(s)
2) Clean air filter and MAF sensor
2) Time for a new O2 sensor.

[rmmagow]

Driving my wife's Sonata, 42 mpg.

[matthew1]

Driving my wife's Sonata, 42 mpg.

LOL

Seafoam 1x per year, standard crankcase+intake+fuel.

Front O2 sensor, but only after a dip into 16mpg and CE light.

The biggest thing, bigger than all those choices in the poll, is keeping my foot out of the accelerator. Bar none.

[RDEJR]

Do you know if the oxygen sensors or MAF have ever been changed? Especially the front O2 sensor, it can wear out and affect fuel economy without throwing a code.

Also consider some of the other things that can affect air:fuel mixture and cause the engine to run rich - Does your car warm up quickly to normal operating temps on the gauge (i.e. is the thermostat good)? Has the ECT ever been replaced?

Clogged cat or otherwise clogged exhaust?

It is so frustrating to just throw parts at an elusive problem like this, I am not proposing you do that. But maybe get set up with a good OBD tool and check out air mixtures and O2 sensor readings, for starters. I am not well versed in that area can't offer much more advice if you want to go that route ...

Or maybe that same guy at the same gas station, always dilutes the gas he dispenses the same way

I've been through and achieved an automotive degree, so when I hook up a scanner which will read live data, I can see that the fuel trims are slightly off, but not alarmingly. The O2 sensor seems to be putting out the proper average voltage ( 0.45v) but I can't see how fast it switches, so Im not sure how old or new it may be. With the average being about right, I would imagine that it's working OK. MAF sensor, thats also something which seems to work properly with throttle position change. I can see the flow through the MAF increase numerically on the scanner as I press the accelerator.

The exhaust seems to be nice and clear, I dont have any funky smells and the exhaust coming out seems to be appropriate for the level of throttle. The car warms up just fine (fully warm within 5 minutes of driving down the city streets), I don't live in a hilly area, middle salem and keizer are pretty darn flat.

Like I said, I am completely stumped as to how others get so much better mileage than I do.

My turbo car gets 18 in town average, and touch over 24 on the freeway.