///// What are your MPGs WITH Performance Mods .... IF driving conservatively ? /////

[Andyinchville1]

Hi All,

Most people on this site modify their cars for better performance and that often means more power.... sometimes LOTS more but who can blame them? ....I've been bitten by the bug too! ;-)

Anyways, it seems that these same cars can have their MPG's stay the same OR actually go UP when driven conservatively(when compared to stock ....my assumption is better / fewer pumping losses due to better flowing exhausts, intakes , turbos etc and better optimization of fuel injection via larger injectors , advanced timing etc...).

I am hoping to see if there is a correlation (and I'm pretty sure there is) between performance mods and an increased MPG's when driven "normally" or at least the same as stock in order to see MPG increases or decreases for similar driving.

I am wondering also..... at what point do mods go so far as to negatively affect mileage ? Like maybe an injector gets so big that fuel just dribbles out as opposed to proper atomization etc..

I would like to see how far one can go modding before it results in worse fuel economy if driven conservatively.....(maybe "normally" and not hot rodding around)

To start ,

My car is modified per my signature and I get MPGs per the fuelly link in my signature.

I probably drive slower than most (typically 62 to 66 mph regardless of speed on the highway just to be able to keep speeds at a relative constant over many miles .and because I drive at night when deer are out) .

My MPG's have gone up from stock considerably...

Before any mods, I was typically 46 to 48 mpgs highway

A big MPG boost came from the Tune / Pump / injectors ( I did the 11 mm pump / injectors at the same time since my pump stopped working (at about 315K miles) ... the tune was done before the pump / injectors but I'd have to look for the records on that ) ... got me closer to 50 - 52 MPG and sometimes a tiny little bit past it).

Somewhere in here I upgraded tire size to 205 70R 15 then again to 205 75 R15 for more overdrive effect ... this helped alot ... in direct correlation to the increased diameter! .... a "free" mod if you need tires anyways. Somewhere in here 3" exhaust was added .... This got me into the 52 to 54 mpg range.

My last round of mods (BRM intake , upgraded SMIC, 3 Bar MAP) has pushed me up to tanks in the 54-56 MPG range ... I am thinking there is more to be gotten because I am not as modded nearly as much as many on this site..

What kind of highway MPGs are you getting and what are your mods? (also , what were you getting before your mods?)

Thanks in advance for any and all help.

Andrew

 

[JohnTF]

Too early for me to add much , but adding to the base - because I just started , bought about 2 1/2 weeks ago with 228,000 miles , 1st top off after about couple hundred miles with under car cover removed [ remember auto trans ] about 32 mpg , trans filter & fluid top-off [ was about 1 1/2 liters low ] , put the after-market aluminum bottom & side plates replaced - got about 34 mpg .
Having a hard cold start [ and after sitting overnight ] issue , the glow plug only come on with unplugging coolant sensor - then starts much easier , but a little ruff for a moment .
Also timing about 42-44 , little retarded .
Tires 205/65/15 low maybe 10,000 on tires Michelins .

A few yrs. ago I heard of someone in southern MN getting about 80 mpg ???

Have to keep in mind [ having the math & data ] how much BTU's are in fuel and - work needed to move car , as an example some of the wives-tales I heard 150 + mpg from carburetor & other stories , the off the top of head figures for BTU etc. / along with a car with specific weight & wind resistance , getting around 75 mpg , is a very ruff max ?

 

[2002_auto_tdi]

Hi All,

Most people on this site modify their cars for better performance and that often means more power.... sometimes LOTS more but who can blame them? ....I've been bitten by the bug too! ;-)

Anyways, it seems that these same cars can have their MPG's stay the same OR actually go UP when driven conservatively(when compared to stock ....my assumption is better / fewer pumping losses due to better flowing exhausts, intakes , turbos etc and better optimization of fuel injection via larger injectors , advanced timing etc...).

I am hoping to see if there is a correlation (and I'm pretty sure there is) between performance mods and an increased MPG's when driven "normally" or at least the same as stock in order to see MPG increases or decreases for similar driving.

I am wondering also..... at what point do mods go so far as to negatively affect mileage ? Like maybe an injector gets so big that fuel just dribbles out as opposed to proper atomization etc..

I would like to see how far one can go modding before it results in worse fuel economy if driven conservatively.....(maybe "normally" and not hot rodding around)

To start ,

My car is modified per my signature and I get MPGs per the fuelly link in my signature.

I probably drive slower than most (typically 62 to 66 mph regardless of speed on the highway just to be able to keep speeds at a relative constant over many miles .and because I drive at night when deer are out) .

My MPG's have gone up from stock considerably...

Before any mods, I was typically 46 to 48 mpgs highway

A big MPG boost came from the Tune / Pump / injectors ( I did the 11 mm pump / injectors at the same time since my pump stopped working (at about 315K miles) ... the tune was done before the pump / injectors but I'd have to look for the records on that ) ... got me closer to 50 - 52 MPG and sometimes a tiny little bit past it).

Somewhere in here I upgraded tire size to 205 70R 15 then again to 205 75 R15 for more overdrive effect ... this helped alot ... in direct correlation to the increased diameter! .... a "free" mod if you need tires anyways. Somewhere in here 3" exhaust was added .... This got me into the 52 to 54 mpg range.

My last round of mods (BRM intake , upgraded SMIC, 3 Bar MAP) has pushed me up to tanks in the 54-56 MPG range ... I am thinking there is more to be gotten because I am not as modded nearly as much as many on this site..

What kind of highway MPGs are you getting and what are your mods? (also , what were you getting before your mods?)

Thanks in advance for any and all help.

Andrew

Great post.

 

[burpod]

my mk3 jetta, previously with: vnt 17/22, pp764s, 11mm alh pump, fmic with 2" tubing pd130 intake no egr no asv, no AC, 26psi requested tune, facet inline "lift pump", stock block and stock head. 195/65/15 tires (8% larger circumference which checks out according to gps measurements) + .681 5th gear CTN trans.

with non-winter fuel i would routinely get 55+ mpg on tanks where it was majority of miles on the highway and keeping speeds generally around 65-75 actual (taking into account the larger tires) and not beating on it too much, just the occasional italian tune up. more aggressive driving and more suburban driving i could sometimes see as low as 45.

since then, and i never got a chance to get any good readings, i installed .260 injectors and a real mk4 lift pump. now, since my timing belt slip it's getting forged rods, asv pistons, ported head with stage3 colt cam stiffer valve springs and 1856 turbo. also re-installing AC. i will be very bummed if i see much of a mileage drop. i don't think i will if driven normally. can't wait to finish getting it back together and broken in

 

[GlowBugTDI]

27mpg...

Hoping 50ish once i fix the problem.
You read my 450mi tank thread though so you know i got problems here lol.

 

[scooperhsd]

At least as good as stock for MPG (45+ MPG on highway, 40-42 in KC city / suburban driving) when driven conservatively (with traffic). Stock sized tires (205/55 HR 16) at recommended pressure.
Mods - 5 speed manual (no special gears / stock final drive)
much larger Fuel injector Nozzles
RC2 (special - in light of fuel injector nozzles, it's pretty close to stock below 3000 RPM to minimize smoke)
3 inch exhaust

 

[IndigoBlueWagon]

Stock turbo, 11mm pump, PP357s, lift pump, RC3+, PD150 snorkel, airbox, and turbo inlet, 2" downpipe no cat, stock exhaust.

This is from a particularly good run of fill ups year before last:

Included a trip to WI and one to NC, I think.

 

[Nevada_TDI]

I drive moderately around town and I cannot seem to get my city average above 38 MPG, and I have not been able to get highway miles yet.
I have new .216 nozzles setup by Frank, and a 24 PSI conservative fuel tune. I have changed my IQ from 4.2 to 6.5 and felt no loss of power and a very slight haze at WOT. Timing is slightly advanced too.
What should I do next is my quandary. I see members here getting way better FE with similar hardware and tunes, and I cannot figure out how they do it.

 

[scooperhsd]

I drive moderately around town and I cannot seem to get my city average above 38 MPG, and I have not been able to get highway miles yet.
I have new .216 nozzles setup by Frank, and a 24 PSI conservative fuel tune. I have changed my IQ from 4.2 to 6.5 and felt no loss of power and a very slight haze at WOT. Timing is slightly advanced too.
What should I do next is my quandary. I see members here getting way better FE with similar hardware and tunes, and I cannot figure out how they do it.

Automatic ? You're doing about as well as you can get.

5 speed manual ? Well - city driving is by nature not going to get the MPG of highway driving / mixed driving.

 

[IndigoBlueWagon]

I drive moderately around town and I cannot seem to get my city average above 38 MPG, and I have not been able to get highway miles yet.
I have new .216 nozzles setup by Frank, and a 24 PSI conservative fuel tune. I have changed my IQ from 4.2 to 6.5 and felt no loss of power and a very slight haze at WOT. Timing is slightly advanced too.
What should I do next is my quandary. I see members here getting way better FE with similar hardware and tunes, and I cannot figure out how they do it.

There's a TDI owner around here with a similar setup and similar FE. Like with is car, I think if your mileage is that low then something's wrong. Track days aside, I can think if two incidences where I've gotten less than 40 MPG in my wagon: once was driving to PA into a near hurricane, and one was driving across ND with the cruise set at 85 and the A/C on. Otherwise, regardless of mods, I've always gotten low 40s at worst, 50ish at best.

 

[Nevada_TDI]

IBW, thank you for your response. I have been pulling out what little hair I have left trying to figure out what the source of the problem is.
My tires are all at proper pressure...the only thing I have not done lately is checking the temperature of the brake rotors when get out of the car. I just checked the rotors, and they all in the middle 80's.
I will see if there is anything I missed; the cost of a new tune to gain 5 MPG would likely take years to recover, so I will check again.

 

[scooperhsd]

Tuesday I made a highway run (225 Miles) and wednesday came home - Ran the speed limit on cruise control (65-75 MPH). Overall MPG for the trip (single tank) 42.9 . Not bad all things considered (state of tune, speed, miles on car (377,000), stock tires size at 30 PSI).

 

[2004LB7]

I normally get low 40s but have gotten high 40s before timing belt replacement so I need to check the timing. Mostly city and back roads to work. Maybe 5-10% highway total.

 

[NewTdi]

I keep a very accurate mileage log for both my near stock and not so stock ALH cars.

With my sedan that has RC3, Borg Warner "S7", PP764, and PD150 TIP the mileage is approximately 46mpg when driven around 65mph on the highway with an average tank speed of 46mph and an overall 80/20 freeway/city driving. Pre-mods my car was averaging 52-54mpg on the same roads. I am trying to figure out why most people see an increase in mileage after getting modded while my results have give in the other direction. The old rule of 60mph/60mpg was spot on pre-mods. Now I would have to say that the new norm is 60mph/50mpg. With the sedan I have driven the same roads and routes all along since new.

With my wagon mileage is a little bit better and I do have the following mods: Malone stage 3, 11mm pump and a taller 5th. The best tank ever was 57mpg at am average tank speed of 57mph, 98% highway driving from Phoenix to San Francisco. Car is usually loaded with 500lbs or more of work stuff. The average mileage for the past 14 months given all types of driving has been 47.15mpg for an overall average speed of 52.17mph over the course of 91561 miles.

Tires have always been inflated at 38psi. I recently changed from 195/65/15 to 205/55/16 and the mileage has dropped by 2-3mpg on the last 3 tanks. Costco did not want to sell me 195/65/16 which I think would have resulted in the same mileage as the 15" tire.

The biggest drop in mileage I feel came from the PD150 TIP install. The car's performance with that mod woke up like there was no tomorrow. Pre PD150TIP the fuel efficiency was about 3mpg higher.

I think I might install a taller 5th speed in the sedan as well since it does make long distance driving much more pleasurable.

I have been using both Penthosin and Redline oils with no noticeable change in mileage however with Redline oil the consumption is slightly higher; with the Penthosin I will add slightly less than a quart of oil for 10000 miles while with the Redline I add just a hair above 1 quart for the same distance traveled.

 

[IndigoBlueWagon]

The biggest drop in mileage I feel came from the PD150 TIP install. The car's performance with that mod woke up like there was no tomorrow. Pre PD150TIP the fuel efficiency was about 3mpg higher.

Did you have the air tables in your tune adjusted when you swapped TIPs? The PD150 MAF flows more air but at slower speed, reducing fueling. That may be affecting your FE.

 

[NewTdi]

Did you have the air tables in your tune adjusted when you swapped TIPs? The PD150 MAF flows more air but at slower speed, reducing fueling. That may be affecting your FE.

Originally Jeff's tune was for a VNT17 and I ended up replacing it with a Borg Warner however the tune was written for a PD150TIP/MAF. Time to see end in the ECU for a re-write

 

[geezer88]

I've got a stock, 2002 Jetta, auto transmission, stock size tires, 140K total miles, two adults, some baggage.

On trips to Arizona from Oregon I get 40-44 mpg.

15 mile round trips to town for shopping drops to 30-34 mpg.

tom

 

[Mongler98]

8mpg track
25mpg the way I like to drive recklessly back roads
38mpg with mostly highway 80mph
62 cross country all highway non stop at 68mph
48mpg average if I grandma
230hp nasty stage 6 gt2052 764s and lots of lol

 

[Andyinchville1]

I keep a very accurate mileage log for both my near stock and not so stock ALH cars.

With my sedan that has RC3, Borg Warner "S7", PP764, and PD150 TIP the mileage is approximately 46mpg when driven around 65mph on the highway with an average tank speed of 46mph and an overall 80/20 freeway/city driving. Pre-mods my car was averaging 52-54mpg on the same roads. I am trying to figure out why most people see an increase in mileage after getting modded while my results have give in the other direction. The old rule of 60mph/60mpg was spot on pre-mods. Now I would have to say that the new norm is 60mph/50mpg. With the sedan I have driven the same roads and routes all along since new.

With my wagon mileage is a little bit better and I do have the following mods: Malone stage 3, 11mm pump and a taller 5th. The best tank ever was 57mpg at am average tank speed of 57mph, 98% highway driving from Phoenix to San Francisco. Car is usually loaded with 500lbs or more of work stuff. The average mileage for the past 14 months given all types of driving has been 47.15mpg for an overall average speed of 52.17mph over the course of 91561 miles.

Tires have always been inflated at 38psi. I recently changed from 195/65/15 to 205/55/16 and the mileage has dropped by 2-3mpg on the last 3 tanks. Costco did not want to sell me 195/65/16 which I think would have resulted in the same mileage as the 15" tire.

The biggest drop in mileage I feel came from the PD150 TIP install. The car's performance with that mod woke up like there was no tomorrow. Pre PD150TIP the fuel efficiency was about 3mpg higher.

I think I might install a taller 5th speed in the sedan as well since it does make long distance driving much more pleasurable.

I have been using both Penthosin and Redline oils with no noticeable change in mileage however with Redline oil the consumption is slightly higher; with the Penthosin I will add slightly less than a quart of oil for 10000 miles while with the Redline I add just a hair above 1 quart for the same distance traveled.

Hi

Interesting info.

On your tire situation, I Googled a tire size comparison calculator and apparently the new tires you have are actually .4% smaller in circumference wise then factory size .... for all practical purposes probably pretty much the same but if unadjusted in mpg calculations could have potentially increased mileage slightly had all the other numbers remained the same.

My guests for the decrease in fuel economy is possibly two fold.

1) maybe Wheel and Tire combination weight went up? Small Rubber and 15 in Avis Wheels are a fairly light combination what wheels and tires did you end up going with? Any idea on weight? I think the weight matters more in stop-and-go driving that it does necessarily on steady-state speeds

2) the Tire Choice also could impact fuel mileage .... what make and model Tire 15s were you running versus what make and model 16 inch tires are you currently running? My guess is maybe a performance-oriented 16 inch tire would have more rolling resistance than what you were running?

I did my tire modification a different way ....

I simply went up in size from Factory all the way to 205 75 R15 so far

I did choose my tire based on weight and PSI rating when cold .... after researching everything I ended up with a 51 PSI cold rated Hankook kinergy tires .... next go-round I'm going same brand / model but next size up 215 75 R15 for an increased 2% diameter for better overdrive effect.

To be honest I'm not sure a small increase in width makes that much difference since my first step up was 205 70 R15 in the ecopia low-rolling-resistance tires ... I'm guessing because of the l r r rating and the overall larger-diameter had more than offset the 10 mm increase in tire width.

Although the Hankook Tires are not rated lrr I think overall the high tire PSI cold rating and latger circumference / diameter more than makes up for the increased width and lack of lrr designation.

As far as the pd150 turbo inlet pipe I like the fact that it increased performance markedly ( which I assumed better flow would ) but I was somewhat taken back by the fact that you found fewer MPGs as a result.

Originally, I ordered a 3 inch turbo inlet pipe from profi diesel ( looked even freer flowing than the pd150 tip) but due to me not receiving it I ended up buying a pd150 turbo inlet pipe along with airbox excetera.

I was really looking forward to getting that on the car with the expectation that both MPGs and performance would increase.

About the only thing I can think of is maybe the larger mass air flow sensor without being properly retuned is causing some sort of issue that results in lower MPGs?

I think I read somewhere when the intake piping is increased to 3 in diameter the mass air flow sensor sees a lower volume of air moving because of the bigger piping and somehow makes adjustments that are incorrect based off of it not being retuned?

Andrew

 

[millere5815]

Mine consistently got better with more power, even maintaining over 50mpg in out Ohio winters. You can read more about it if you click on the ecomodder banner in my sig. Lots of details there.

Best mod I ever did was swapping to a 5 speed with a taller 5th gear.

 

[Andyinchville1]

Mine consistently got better with more power, even maintaining over 50mpg in out Ohio winters. You can read more about it if you click on the ecomodder banner in my sig. Lots of details there.

Best mod I ever did was swapping to a 5 speed with a taller 5th gear.

HI,

I liked reading your fuelly info.... what are the 2 rows of numbers under what I think are the odometer readings ?

It was interesting to see your numbers for the upgraded intake manifold and SMIC were in line with what I found.

I have not yet upgraded the intercooler piping but it was interesting to see you did the 1.8T pancake pipe mod.

Thanks

Andrew

 

[millere5815]

I liked reading your fuelly info.... what are the 2 rows of numbers under what I think are the odometer readings ?

Yes, the multiple consecutive numbers are the mileage numbers at each mark on the fuel gauge. First number is when it finally moved off of full, last number is when the fuel light would turn on. I was a little anal on watching my fuel. At the time, I could almost tell how the weather was in between marks. Colder/rain would reduce the miles between.

Towards the end, the car started running a little worse, and seemed down on power. Never did find out why

 

[DivineChaos]

With my perminantly fixed mk6 jsw. I have seen 52mpg with it on a 80 mile trip. If I drive easy and do the speed limit I see 44mpg. How I usually drive I average 38-42mpg. About 520 miles before the light. I'm stage 2 turbo back exhaust. And a modified intake because factory one broke.

 

[UhOh]

Logged over 101k miles. Car is now just breaking in: 220k miles. Have had DLC520s and a Malone Stage 2 tune for the last 80k miles. 5spd. Last 5 of 6 fill-ups have recorded 800+ mile tanks and about 55.5 mpg. Mostly highway driving, but have been driving more gently because I've been hitting a lot more traffic (road construction). Everything on my car works as smooth as smooth can get (exception is the 2nd gear sychro!). Best mpg I have gotten is 58.1 a couple years back and I'm figuring that if I were to try I could likely beat that.

 

[jmodge]

Last two tanks on the Tacoma were 34.7 and 35.5, calculated by gps. Included a trip through Chicago and traveling back and forth to GR.

 

[Dooby6]

2010 skoda octavia 1.9 Pd105, stage 1 remap with dyno =151.8bhp, 349nm, 225/45 r17 tires, 5 speed manual gearbox.. 4.1ltrs/100km or 57 us/mpg conservative, currently on 308,000km, remap at 240,000km

 

[DivineChaos]

Stage 2 delete 2.5" downpipe through resonator no muffler. I didn't notice a diff in my mg. If I drive light. 65mph I can get 45mpg

 

[tjg]

2013 A3: CR170 Stage 3 delete, CP3, 15lb wheels.
65mph gets around 44-45mpg
75-80mph gets around 39-41mpg

 

[[486]]

stock 02 golf 42 or thereabouts
moderate sized turbos (1752S atop a td04hl19t) and pp764 nozzles 45 ish
tdo4hl19t atop an hx40 and dss .360s got 48ish
cut the piston bowls and that brought it back down around 44
crappy waste oil fuel brought it down further to 38-40 but at that point economy became irrelevant
I generally set the cruise at 75 and don't waste any time getting there.

 

[IndigoBlueWagon]

Here's my last fill-up

Mild weather, little or no A/C, I tried to keep it under 80 on the highway, and a fair amount of gentle suburban driving on this tank. Still, I was surprised. It will need another fill up in the next couple days and I'll report back if this was an underfill, even though I did see clear fuel in the filler neck.