First impressions: GDE Eco Tune

Ordered yesterday, arrived today. Had to ring it out and see if there were noticeable improvements via "seat-of-the-pants" feel before doing MPG testing. So far the extra power is there and very noticeable, and in the 80mi of spirited driving/testing I did today, the fuel gauge barely moved. I was already 300mi into this tank and started the day out sitting exactly on 3/4 tank. Past experience tells me it would result in a 46-47mpg tank if nothing changed. Needle Is still above 5/8, where normally it would be just below it with current miles. So far their claimed mpg results seem legit. But won't know exactly until more driving is done. Should know better by tomorrow, as I have a 300mi business trip planned and will be a good indicator of what the rest of the tank holds on store.

I'll get more detailed mileage figures as the miles track up. I'll keep everyone updated.

At the 5/8 full mark now, and odo is reading 441mi. Previous best ever at this point on a 48.1mpg tank was 435. Conservatively guesstimating my current fuel mileage over the past 120mi to be right at 51-52mpg.

Crossed the 1/2 tank mark @ 510mi a 16mi improvement over my best at this point of 494mi @ 48.1mpg

3/8's came at 598mi, increasing my improvement over the 48mpg tank to 18mi. Was raining some this leg which allways cuts into my fuel mileage.

Passed the 1/4 tank mark @ 676mi. with a continued improvement of 31mi over my previous best of 645mi at this point on the 48mpg tank. Don't think I'll break into the elusive 900mi. club just yet, (as I need a bare minimum of 51.7mpg throughout the tank) but still hoping the overall average will cross the 50mpg barrier.

The tank average will be interesting. Are you still using the winter blend fuel at your location? Warmer temps will also help. Summertime is the best for overall fuel economy.

Low fuel warning tripped @ 806mi. Now, I'm tempted to make that run to 900mi. as it seems an 800mi. LFWL is the benchmark that others use to determine if they should or not. Think I'll get a gallon jug of fuel and go for it.

It's hard to say, as I filled in Chattanooga, TN and the I-40 corridor is notorious for late changeover. I personally think it's summer blend, as my guestimated average before tuning was up by 3mpg vs. the previous tank. Which I know fir certain was winter blend.

Wow. Those are great numbers. I wish the ALH with GDE tune made as dramatic a difference. And this is an auto tranny!?

SFHGolfTDI said:

Wow. Those are great numbers. I wish the ALH with GDE tune made as dramatic a difference. And this is an auto tranny!?

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Yes, I have the 5spd auto tranny. Bone stock except for a K&N air filter, muffler delete, and now GDE Eco tune. No hyper-mileing either. I simply set the cruise on 60mph on the highways and shift into neutral at long red lights.

diesel_fan77 said:

Yes, I have the 5spd auto tranny. Bone stock except for a K&N air filter, muffler delete, and now GDE Eco tune. No hyper-mileing either. I simply set the cruise on 60mph on the highways and shift into neutral at long red lights.

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You might be aware of this already, but you might want to reconsider that K&N. Search around on that one.

diesel_fan77 said:

Yes, I have the 5spd auto tranny. Bone stock except for a K&N air filter, muffler delete, and now GDE Eco tune. No hyper-mileing either. I simply set the cruise on 60mph on the highways and shift into neutral at long red lights.

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Keep the car in gear when coasting to a red light, you'll use less fuel then if you put it in neutral.

SFHGolfTDI said:

You might be aware of this already, but you might want to reconsider that K&N. Search around on that one.

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Yeah, it's what came with the car and been too lazy to change it.........LOL!!!

LNXGUY said:

Keep the car in gear when coasting to a red light, you'll use less fuel then if you put it in neutral.

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I always coast in gear, only idle in neutral during long red light waits.


I'll know more when I get home after calibrating my ODO via GPS, but by all accounts I'm pretty certain I broke the 50mpg barrier fir the tank average. I did not however make the 900mi club, as I ran out of fuel just shy of that goal

Before I posted here with my official numbers, I needed to re-confirm my odometer's error of +1.5% which I last checked against my GPS about 5mo ago. And so it is still. All figures factor in this error correction.

Ran out of fuel while trying for the 900mi. Club @ 874.9mi (odo read exactly 862mi) from past experience,I know that this happens after exactly 17.4 gal have been consumed.

874.9mi ÷ 17.4gal used = 50.28mpg


Put my gallon in the tank, and drove to the station I had originally planned to fuel at which I knew would work out to be exactly 887mi via odometer (901mi gps). Top off took 16.91gal. Add the 1gal I dropped in the tank after running out, and it comes to 17.91 gal consumed in 901mi traveled.

901mi ÷ 17.91gal used = 50.30mpg

Wow, awesome numbers man, especially with the auto. I've been lookingat GDE's tunes for awhile so this is an awesome share! What are your initial feelings compared to stock/before?

Power, when needed and/or wanted, is definitely there and very noticeable over stock

Breaking down the numbers into more detail this morning, I came up with a relatively conservative guestimate of 52mpg for my running average post-tune. Using a bit of simple algebra, and using past experience of what the first 308mi would have yielded here's a simplified equation of what I computed:

308mi @ 47mpg
593mi @ 52mpg

Now, seeing that 308mi is almost exactly 1/3 of the total miles driven of 901mi, we use that figure in the first part of a three number average.

(47 + 52 + 52) ÷ 3 = 50.3mpg

My highest MPG on the HOT TUNE with all highway was 53.38.

I'd love to hear from more ALH owners about their mileage. I find it interesting how much more can be gained with a PD.

SFHGolfTDI said:

I'd love to hear from more ALH owners about their mileage. I find it interesting how much more can be gained with a PD.

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After talking with Keith at length about this, the reason is that the PD had far more electronically controlled systems that can be programmed via the ECM vs. the more mechanical ALH. That, and the ALH from the factory is a more efficient engine. So not as much to tweek/gain via ECM flashes.

With some obvious left-over winter blend fuel from my last fill-up, and colder than normal temps recently, my first full tank on the tune averaged 48.5mpg.........Still, a significant improvement.

Good to see. What kind of driving style was that with? Do you have any additional averages from more recent fill ups?

I too have a GDE ECO tune, my best tank ever was 46mpg on a 600+ mile trip to Montreal. 90% highway, averaging 70mph.

I was hoping I'd be getting a bit more. Not sure if anything else needs to be addressed.

My driving style does tend to be 50/50 short trips, and longer highway drives, so I'm sure that has an effect.

I did the rear brakes and calipers recently because the right one was sticking. Next will be 2 new front bearings as they are making noise; I heard those car rob MPGs as well.

I really want to be able to get my hands on a VCDS so I can see what kind of parameters I'm dealing with.

Anyway, thanks in advance for any input.

Peter