My quest for 25 mpg in the GLX

[dubstyles240]

i love gas economy discussions. Ecomodder.com does have a lot of good threads on how to sip the gas and lots of diy ideas that are very interesting, i've tried a few of the ridiculous ones and they work. Isn't there an eco cam you can replace stock cam with to get a little better fuel economy, do a tdi 5th gear, other small tricks?

Good luck with your experiments, I'm interested.

I wouldn't think a TDI fifth gear is a small trick! I've been meaning to check out ecomodder (previous poster has intrigued me), so I'll see what they have to offer.

Part of the point is to keep my car relatively how it is (no weight reductions, aero), and not to spend much money in order to save money, outside of regular maintenance like plugs/filter/wires.

Speaking of wires... I've realized that the wires I bought in late 2009 are pieces of sh*t. They're Xact brand, and one is arcing to the head at low RPMs, and another one is pretty loose on the spark plug. Google search yielded a LOT of bad reviews. They're under "limited lifetime warranty" from Advance, so I'll either try and get a new set, or just drop $60 on some Bosch wires I found on Amazon. Somehow I paid $120 for these current wires and I can't remember why I didn't price shop, or check reviews on the brand.

[Stealth_TDI]

Hello,

I don't know how accurate it is, but my mfa usually says I'm getting 32 mpg while going 65.

MFA's are usually optimistic to make a driver feel good. The only accurate way to measure MPGs is to divide the number of miles driven by the number of gallons added. A cool thing about diesels is you can fill the tank right to the brim every time for a consistent measurement.

I don't agree with the "coast in neutral" idea... I was taught that leaving the car in gear and staying off both the gas and brake will lead to the best fuel economy. And the reason for that is because as the car is rolling in gear, the engine shuts off the fuel injectors and you don't use any gas at all. Whereas if you're rolling in neutral, the engine is constantly sipping on fuel.

^^^ THIS! If you wind up getting a ScanGaugeII, then you'll be able to prove or disprove this in your VR6 application by actually monitoring your fuel flow (I think it measures in GPH). My injectors shut off when coasting in gear. What I haven't measured is whether driving in gear on a slight downhill consumes less fuel than coasting in neutral. I just let the cruise control handle that. But I'll measure it someday now that I'm thinking of it.

Good Luck!

[Bariman82]

This is one of those things that varies from car to car and folks like to say that all modern cars shut off fuel under decel. My 2.0 does NOT shut off fuel flow when coasting in gear. ScanGauge and UltraGauge can be set up to display instantaneous gallons per hour. It's a measure of what is actually being injected. When warmed up, my engine idles at about 0.25 gal/hour. Coasting in gear is close, but not as efficient; around 0.30 gal/hour. The car also coasts MUCH further in neutral than in gear, so it's a win-win situation.

[dsleggett]

Swap in a 2.0, keep your VR6 to replace later. You should be able to find an 8v pretty cheap. You can drive the 2.0 as hard as you want and end up with 30+ mpg, I did it for a few years, 35 miles each way on my commute. I generally hit 90 mph for a few miles at a time and still returned 30+ mpg. 70/30 mix of highway and city.

[KeatGLX]

hmm, i have a 1995 GLX, 5spd with all options and if i drive normally (not whipping around town) my MFA registers 27mpg on 45 and 30 mph roads. i think the free flowing and air intake help a bit. I like the car btw

[X37]

Gotta get that Nitrogen air in tour tires and an ebay chip and the little turbine thing in the intake boot. 45mpg or none of your money back!

Sent from my SGH-T989 using Tapatalk

[coolalex]

I'm getting solid 30.

Sent from my ADR6400L using Tapatalk

[dubstyles240]

Bariman82

The car also coasts MUCH further in neutral than in gear, so it's a win-win situation.

My point exactly. I actually tested this out on an area that I can consistently coast for ~.9 miles, and in 5th gear, I coasted .2 before I was going too slow for traffic. Going to look into a gauge, seems like it would be a great indicator.

Swap in a 2.0, keep your VR6 to replace later. You should be able to find an 8v pretty cheap.

Would be much cheaper to pay for worse gas mileage I'd think. I'm a decent DIY mechanic, but not up for a motor swap, so I'd have to pay someone to do it. Again, part of the point is that I love the VR sound and having the power available if I need it.


No picture update, but I've burned just over 3/8ths of a tank of the premium, and am at about 140 miles. I learned from last time though, that the gauge seems to make the tank look slightly more empty than it is... so I could be about on pace for a 380-400 mile tank!

[wanderer1983]

This will sound ridiculous, but on another audi forum, a poster said that accelerating as fast as possible saves more fuel than accelerating very slowly as you are able to get to cruising speed in much less time. I have not personally tried this method but he and a few others swear by it. Keep in mind this is with a 2.2L 20VT engine running anywhere from 20-28psi at full throttle in a car weighing 4000ish lbs . Also, if you go around corners faster, while maintaining safety of course, you dont have to accelerate as much after the corner, plus its fun . Not sure if it was mentioned earlier in the post, but you should also keep an eye on your tire pressure.

[sk8too]

My last tank with out trying I got 23mpg...just sayin


Boo ya tapatalk! If you haven't got it yet get it!

[GTInoob]

I normally get 26mpg with spirited driving and 30+ with calm driving in my 98 GTI VR6. Also, using the engine to decel actually saves more fuel than idling. The ecu cuts fuel during decel while in gear until around 1000rpm. Pushing in the clutch and idling to a stop is wasting fuel.
Try it and you will see the difference.

[JohnStamos]

30mpg average in a 12v is cake. Add in alot of traffic, and 25 is easily achievable.


Mk3 12v's stock average about .5 gallons a hour at idle.

Above 2200rpm the injectors are shut off on decel. Below that they are ramped back on to help with throttle tip in from off throttle.

12v's engine brake aggressively, so most of the time coasting is a better option, steep downgrades where you need to scrub speed anyway are the obvious exception.




I can do 30 mixed easy in centralish PA living in the middle of nowhere, with roads that don't have less then a 5% incline for more then 300 feet at a time, and thats getting on it a few times.

35 highway is my high average for highway, and 32 is normal highway if not really thinking about saving gas. and thats on wide aggressive summer tires and 190whp.

These cars can do well on MPG if you keep them maintained and know how to drive them.

[n0rdicalex.]

30mpg average in a 12v is cake. 35 highway is my high average for highway, and 32 is normal highway if not really thinking about saving gas. and thats on wide aggressive summer tires and 190whp.

These cars can do well on MPG if you keep them maintained and know how to drive them.

this.

i remember so many trips to and from our lake cottage where i averaged ~33mpg.

[Mateusz-Dubs]

im getting 28-30 mpg. nothing major, mk4 head gasket cat back, intake. what fuel are you running too?

[sk8too]

Ahhh yes, you are running premium with no ethanol right?


Boo ya tapatalk! If you haven't got it yet get it!

[12V_VR]

Above 2200rpm the injectors are shut off on decel. Below that they are ramped back on to help with throttle tip in from off throttle.

also the injectors will continue to stay off till about 1300rpm when they turn back on

[n0rdicalex.]

Ahhh yes, you are running premium with no ethanol right?

most fuel has around 5% ethanol in it nowadays anyway, and 10% ethanol is becoming more common on some states/cities.

[JohnStamos]

E10 only causes a 3-4% mileage reduction.


And blends of around E40, are much cheaper per mile, then E10 and pure gas.



Also, alot of Premium grade fuel is ethanol free.

[MisterMK3]

I'm very interested to learn what kind of mileage you really can get out of a GLX. Just sold my TDI that got 45 mpg without even trying, and bought a GLX. So... yeah I'm definitely going to be taking a hit on the mpg. haha. Keep it updated!

[dubstyles240]

I burned a little over half of the premium gas (93 oct), so I filled up on my way to work this morning. I've been using the same pump at the same station for the entirety of this thread, in an effort to cut down on fluctuations from topping off.

Anyway, after 187.2 miles, it took 7.29 gallons to fill her back up. 25.7 MPG. This is a .2MPG increase from regular to premium (which could be due to driving style, conditions, etc.). So I'm not ready to say definitively one way or another, but at first glance, it doesn't look like using 93 over 87 octane proved to give any better MPG (although I'm sure it's better for the engine anyway).

NGK wires just came in today at Advance, and I'm going to pick up NGK OEM plugs from New German some day this week (maybe even Saturday), so I'll keep you all posted.

[coolalex]

I put in 91 last night as well to see if it raises my 30 at all. Will post results

Sent from my ADR6400L using Tapatalk

[Stealth_TDI]

I just thought about something as I see some really good MPG claims: Those running shorter tires than stock to achieve "moar low" really aren't driving as far between fill-ups as they think. A 195/45R15 is 6% shorter than stock. A stretched 165/50R15 is 7.5% shorter. On a 350-mile tank, that equates to 20-25 miles that aren't being driven but are being credited to padded MPGs. IOW, that 30-mpg tank is actually closer to 28. It's not much of a difference... but a difference nonetheless.

Of course, all of this is pointless if the odometer has been calibrated specically to the new tire size. Check your odometer against a GPS to see the difference.

[v-dubkyle]

my VR 12v..

put $50 of surprem(1.40 per liter) (91 oct, highest grade fuel in nova scotia, canada) which is approx 35 liters or about 9.4gallons of gas. car wasnt empty when i put gas in it.. just above the orange. when i put 50$ into it it increased the fuel gauge up between 3/4 and 7/8s. and so far i got about 220kms in town driving on it.. light foot and heavy foot driving. car is now just a tad under 1/4. My car also been having a few problems with idle, idling to high.

[veedubbd]

best ive done is 650kms to a tank and there was still some runtime left. 2L with an intake, exhaust and I midly ported the TB. for the record the TB not only incresed performance but also milage and ive had no side affects (ie: bucking)

[Filthydubber]

I was taught that leaving the car in gear and staying off both the gas and brake will lead to the best fuel economy. And the reason for that is because as the car is rolling in gear, the engine shuts off the fuel injectors and you don't use any gas at all. Whereas if you're rolling in neutral, the engine is constantly sipping on fuel.


I'd be interested in hearing progress updates so don't forget to be updating this thread. And remember, it's BEST TO COAST IN GEAR.

^ This is 100% correct.

[dubstyles240]

^ This is 100% correct.

I don't think anyone's disputing that fact any longer. But it seems like everyone agrees that you can't coast in gear for more than .2 or .3 miles before slowing down to almost a stop, and you can't roll in 5th on the highway at all really, you'll go from 70 mph to 50 mph before .1 mile. So rolling in neutral IS beneficial if you can get a mile or so out of it.

Anyway, the odometer on my last tank of gas was wiped out by a battery change (my battery was 7 years old!). I had plugs (NGK Bk5ekru), wires (NGK copper), and the battery done over the weekend. Hit 270 miles right at 1/4 tank left, which puts me on pace for 360 miles, 25 mpg. Seems like that's about what my car is gonna do.

[JohnStamos]

^ This is 100% correct.

Except that its not 100% correct.



Go do some logs, and see the difference for your self.

[MisterMK3]

I know that in a TDI, VAG-COM shows 0.0 liters/hour of fuel use if you're coasting in gear. Coasting in neutral obviously didn't show this, as fuel has to be injected to keep the engine running. However, I'm not sure if that same concept applies in a gas engine. Hmmm...

[Bariman82]

I said this earlier; it depends on the car and the engine. No, not all cars, modern or otherwise, shut off fuel under decel. My 98 2.0 shows 0.25 gal/hour at idle. It shows about 0.30 gal/hour coasting in gear. I also don't go as far coasting in gear, so that's why I coast in neutral. Getting a volume/time number (gal/hour, liter/minute or whatever) from some diagnostic tool (vagcom, scanguage, ultragauge) is how to determine if the car shuts off fuel under decel. That number shows what fuel is actually being injected. It's a definitive test. "I was taught..." and "I think..." are not.

Folks on ecomodder discuss this. On a given car that DOES shut off fuel under decel, is it more efficient to still coast in neutral (going farther per fuel) or coasting in gear (not using any fuel, but not coasting as far)?

[okanTDI]

vr's are great, but I think you should look into finding a tdi. you can get almost double the mpg's without driving like a grandma, and you could get more than double if you tried. think of all the diapers you could buy then. it's also not that hard to make a tdi keep up with a stock vr. they are honestly a lot of fun. YouTube some vr6 vs tdi videos and check out tdiclub forums. you could probably brung your cup kit over too.

[VDub2625]

In, becuase this is a thread idea that really interests me

BTW, i saw you calculated your MPG based on miles driven and tank size. Don't do it based on tank size, do it based on the amount of gas you refill with. Even though I have a 14.5 tank in my Cabrio, I can only get maybe 12-13 at the max in there. The rest is in the reserve tank.

Personally, I'm disappointed in my 2.0... 310-320 is all I can muster, for an average of 26mpg. It is a heavier Cabrio, but still. I need to find out what is wrong. I just did a tune-up (old plugs were WASTED) and I'm 3/4 the way through the first "after" tank, so we'll see where it goes from here.

I don't know why you are showing ANY fuel flow coasting in gear... above 1700rpm, there should be zero fuel flow. Deceleration fuel shutoff, they call it. You will get better MPG coasting in gear at a higher RPM, though you will also engine brake which isn't good if you need to coast for a while.. progressive downshifting can help.

I am reading the thread now, but I wanted to get this out too... do you have a chip? performance chips do eat into MPG becuase they make you want to use the LOL pedal more, but, if you drive efficiently, they actually help improve MPG because the advanced timing takes better advantage of the power in the fuel. So consider one if you don't have one yet. Don't do cams or exhaust mods though. I got 2-3mpg out of my Mk2 16v with a chip, and more power for fun times to boot.

ALso, if you want help fixing the MFA, I can help. If the buttons don't do anything, it's probably an easy fix, and these MFAs are very accurate as they get the MPG reading straight from the ECU, rather than the old way of checking engine vacuum.

[96BlKjEt]

Heh wow thats my car, right down to the airbag light being on, anyway my VR loves gas. I have taken to letting it sit whenever i can and driving my moms little gas sipping elantra wagon around town. I will say on the highway it does good, but using a quarter tank to run 15 miles doing 70, where as the little elantra can make 30 miles with a quarter tank does make me think i shoulda gotte another 2.slo, which will be in my future or a TDI. The VR is good on gas, if driven correctly (my mother has proven this, she shifts around the same RPM i do but gets better mileage then me when we did the experiment)

[coolalex]

This is true. I used to get 20 mpg. Now I get 32. It's all in your habits

Sent from my ADR6400L using Tapatalk

[JohnStamos]

Everyone getting crappy mileage needs to stop giving what they think is "advice".

If you are getting under 35mpg in a 2.0, why would you be trying to tell everyone how to get good mileage?

It is SO easy to get 35mpg in a 5speed ABA. It seriously takes almost no effort. It is laughable how many people in here get terrible mileage in ABA's.




Also, I'm pretty sure Paul was even pulling low 30's highway in a Vr6 Mk3, with 4.24 final, 268's, headwork, ect. Come on guys, mid 20's in a aba?

[OrangeDUB]

Mid 20's in an ABA is very laughable. This whole thread is kinda silly-willy.