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    Thread: Mods to improve VR6 gas mileage?

    1. 04-14-2005 05:16 PM #1
      God forbid, someone ask a practical question on Vortex that isn't performance (or wheel or body kit or Ebonics) related, but here goes...

      Obviously, driving and maintenance habits are the biggest contributors to gas mileage. I'd like to know how to modify my GTI for improved gas mileage! I think this is worthy of some discussion, since Premium Unleaded will be $5/gallon before you know it

      Thoughts?


    2. 04-14-2005 05:22 PM #2
      i have my s-afc tuned lean at part throttle i gained about 2mpg, although i doubt you'd go through the process of installing one just for gas mileage.

    3. 04-14-2005 06:28 PM #3
      TDi 5th gear

    4. Member dcvento's Avatar
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      04-14-2005 07:07 PM #4
      buy a 2.0 errrrr tdi haha yo

    5. 04-14-2005 07:52 PM #5
      Don't mash!

      Keeping oil out of the intake tract will maximum octane, so theoretically you're "saving" gas. I've heard running the car until the gas tank empties, then filling it with pure alcohol/methanol and just running that. Make sure your MAF/air filter/intake tract is clean!


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      04-14-2005 07:55 PM #6
      Before modifying the car to run more efficiently you have to take care of more mundane stuff:
    7. Driving style - Just use the brakes less. Any time you use the breaks that means you're wasting energy. drive such that you don't have to use the brakes and you'll automatically be more fuel efficient! This doesn't mean drive slower - it means drive smarter. Anticipate and choose your speed according to conditions. Coast to a red light. Don't speed up and them slam on the brakes. Drive like grandma. You can save a ton that way!
    8. use cruise control - yes the computer is smarter than you
    9. Change all your filters (oil filter, fuel filter, air filter, etc)
    10. use full synthetic motor oil (probably won't affect fuel economy, but with longer drain intervals you can save money in the long run. Change filter every 5K and oil every 10K - topping off as required in between)
    11. Use fuel injector cleaner at least a bottle prior to each oil change. It makes a big difference in some cars but nothing in others.
    12. Remove the backseats, get rid of the crap in your trunk
    13. Get rid of the spare tire and use run-flat spray cans instead
    14. Keep your tires properly inflated - check at every gas fill-up
    15. get rid of air conditioning or at least turn it off
    16. Check that all electronic fuel-injection sensors are working properly with the VAG-COM device (o2, maf, map, coolant temperature, etc.)


      Ok ok. So you're looking for actual physical modifications rather than driving habits and maintenance items like fuel filters and stuff right? Here are some ideas. You won't like them, but they are ideas nonetheless:

    17. Get a custom detuning chip that limits engine RPMs to 3500. Like an opposite of a GIAC chip. Or use the valet mode in one of those multi-chips.
    18. change the transmission gearing to give lower RPM's (like the TDI 5th gear suggestion)
    19. Get tires with low rolling resistance (note that this affects your handling and grip)
    20. Swap to a more efficient engine like an electric or diesel
    21. Lose weight wherever you can especially on rotationg compoenents (battery, hood, wheels, brakes, flyweel, etc.


      Note that changing to mid-grade or regular gasoline does NOT give you better fuel economy in the MkIV. I tried that a couple years ago. I found that while the gas itself was cheaper, my miles per gallon went down with the lower octane gas, so it just about evened out. But you get more power with the high octane gas since that is what the car is designed for. There is a dyno proving this on here somewhere...



      Modified by phatvw at 5:09 PM 4-14-2005


    22. 04-14-2005 08:58 PM #7

    23. 04-14-2005 09:50 PM #8
      lol

      why are those things still selling???

      good find though! lol


    24. 04-15-2005 01:12 AM #9
      Drive like a grandma if your that worried.. Gas has been whooping my arse lately.. so i did decided to just Slllloowww down, i filled my tank up full on 92 octane. 300 miles later.. i have to refill.. all i did was shift before 2k, well accelerating slowly, but not to slow and putting it into 5th gear around 40ish mph. Also kept my eyes open more.. trickled into traffic lights so that not doing last minute braking just enough to keep me moving w/o coming to a complete stop seems to work wonders for me. During the 340 mile.. i did drive hard sometimes looked like it didnt effect me much though

      btw i also used a octane booster, not for the purpose for increasing mileage, the dealer gave it to me to stop the CEL coming on.. said i had dirty fuel lines.. i killed to birds with one stone, ridded the cel and i got awsome mileage.. i forget the name enviro something.. maybe ill edit later

      Chris


    25. Member 2ohgti's Avatar
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      04-15-2005 02:35 PM #10
      i've slowed down a bit. i use to drive like bat out of hell in my old 2.0, but now i have a vr, i'm a little easier on it. still get on it for a little fun. i don't think vr's are bad on gas.

    26. Member VR6ix's Avatar
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      04-15-2005 09:49 PM #11
      Driving style does most of it, but I've noticed an increase in gas milage after a couple mods:

      Synthetic oil. it helps... marginally
      Cold Air Intake. it helps... a wee bit
      Chip. it helps... a wee bit
      Fresh wash and wax... no, not really

      with those three mods and "normal" city driving I'm getting about 5-10% better milage. Nothing huge but it helps, and when you do ignore milage and let the motor haul you've got a bit more power too.


      Just an add-on question as well: is there any difference in fuel consumption at part throttle vs. full throttle if you shift gears at the same RPM? Ie, floor the gas at 1000 and shift at 2500-3000 rpm. At WOT the ECU doesn't read the O2 sensor... I'm just wondering if the floor-it and short-shift method actually saves gas compared to part-throttle acceleration and waiting longer to get up to speed.

      · ·we're only gonna die for our own arrogance that's why we might as well take our time...
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    27. Member Vdubsolo's Avatar
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      04-16-2005 11:52 AM #12
      I have to say since I have put in my giac chip and ran the car on 93 octane...I have def noticed better gas milage, Im sure that running 93 ocatne Has alot to do with that but it is def better fuel wise vs. before....But if your running stock....My advice would be to drive around in a high gear at a low rpm. Change ur filters..and like others have mentioned..dont floor the gas pedeal...thats the fastest way to kill your gas....Before I chiped the car I did the high gear thing..and it worked fine for me...hope it will for you too.

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      04-16-2005 12:08 PM #13
      There are those who claim (and I am not one of them) that installing an engine grounding kit may your increase gas mileage. It didn't help mine, but I met someone who said installing a grounding kit helped his gas mileage, and he seemed to be a pretty normal guy (i.e., not a flake).
      Kenji

    29. 04-16-2005 01:54 PM #14
      Underdrive Pulleys, lighter wheels/tires and removal of the catalytic converter will help (especially the cat, but thats definitely not for some people)

    30. Member jungle's Avatar
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      04-20-2005 05:57 PM #15
      also coasting....more spefically coasting w/ the car in gear...cuz the ecu turns the injectors off while in gear...w/ the clutch in or the tranny in neutral the injectors are still flowing gas.

      also...these cars are adaptive...mine seems particularly so....if you drive like grandpa, the thing keeps getting better and better mileage (slower too...) and the more i beat on it the worse milage it gets (faster to...)


      Modified by jungle at 5:59 PM 4-20-2005


    31. 04-20-2005 07:45 PM #16
      Quote, originally posted by Kenji »
      There are those who claim (and I am not one of them) that installing an engine grounding kit may your increase gas mileage. It didn't help mine, but I met someone who said installing a grounding kit helped his gas mileage, and he seemed to be a pretty normal guy (i.e., not a flake).

      I just did a long term test on the effect of a grounding kit on the mileage that my VR6 gets. Same type of driving before and after - the only difference was the extra ground wiring. The test included over 28500 miles and nearly 14 months and at the end I learned one thing ...

      ... the grounding kit had ABSOLUTELY NO STATISTICALLY- SIGNIFICANT EFFECT on fuel economy. Here are the numbers:


      NO GROUNDING KIT

      Miles - 13759
      Fuel Economy - 27.145 MPG


      WITH GROUNDING KIT

      Miles - 14807
      Fuel Economy - 27.112 MPG


      That's a difference of only 0.12%, which over the time/mileage span tested, is NO EFFECT by any statistical standard.

      I'll be posting a full write-up on the test as soon as I fin the time.

      Gary


      Modified by VgRt6 at 7:47 PM 4-20-2005


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      04-20-2005 08:46 PM #17
      Quote, originally posted by VgRt6 »
      I just did a long term test on the effect of a grounding kit on the mileage that my VR6 gets. Same type of driving before and after - the only difference was the extra ground wiring. The test included over 28500 miles and nearly 14 months and at the end I learned one thing ...

      ... the grounding kit had ABSOLUTELY NO STATISTICALLY- SIGNIFICANT EFFECT on fuel economy. Here are the numbers:

      Wow. Dude you are always so thorough and a huge asset to the Vortex community!

      Just curious, was there any statistically significant reduction in headlight dimming, car radio sound quality, throttle response delay, or any of the other claimed benefits of a grounding kit on MkIV cars?



    33. 04-20-2005 08:59 PM #18
      Absolutely NOTHING changed on my car. With the grounding wires on, the headlights still dim when the windows are used and the bass really kicks in. No more or less than without the grounding wires though.

      Basically, if someone asked me to drive the car and guess if the kit were or were not installed, I would just be guessing.

      Gary


    34. 04-20-2005 09:31 PM #19
      only thing i noticed w/ my car w/ my grounding kit was the lag shifting from 1st to second gear was significantly reduced. other than that, absolutly no increase in gas milage, no less diming of lights, no better radio reception ect

    35. Member Ed52's Avatar
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      04-20-2005 11:32 PM #20
      To improve rolling resistance
      -go for narrow 65 series tires and inflate to 36 lbs
      -do a brake maintenance check for dragging pads
      -make sure alignment is optimised for close to 0 toe in


      -do an Italian tune up (run it hard intermittently)
      -use small diameter exhaust tubing (for low end torque)
      -shift at lower rpms (2000 to 3000)

      1995 Flash Red GTI 2.8 -<< Not Bagged! - only OEM+ >> I will never be cool like the other kids.
      My new dd is a '10 PWagon - not cool either

    36. 04-23-2005 08:24 PM #21
      Mind was very hard on Gas change wiring last week huge difference.... HUGE! so check spark plug, coil pack wiring and filter.

    37. 04-24-2005 02:01 AM #22
      Quote, originally posted by jungle »
      also coasting....more spefically coasting w/ the car in gear...cuz the ecu turns the injectors off while in gear...w/ the clutch in or the tranny in neutral the injectors are still flowing gas.

      yep afr will be at 21 instead of ~14.7
      but besides driving slower i would say just make sure small things are fine like o2 sensors, plugs and wires, etc, tire pressure too i guess. actually, gas mileage is something you might not want to listen to me about. i get bad mileage


    38. 04-24-2005 09:06 AM #23
      Get some narrow tires...less traction = less rolling resistance. Basically, I'd live with it or sell it.

    39. 04-24-2005 10:15 AM #24
      I wouldn't think that the rolling resistance would play a HUGE factor in gas mileage. If every last bit counts, then sure, but remember you have to BUY new tires, so you are already starting well in the negative for savings.

      I think this because I did some calculations awhile back to prove to some tool that his stock R32 could NOT do 178mph. Basically, you can calculate the power required at the drive wheels to overcome air friction and tire friction. The tire friction was the Normal force on the car times the coefficient of tire friction (which was very small). When the car increases it's speed, the normal force decreases. So once you reach highway speeds, the power (and gasoline) required to overcome tire friction becomes very small. At low speeds, it's more of a factor, but if you can't keep your foot out of it, you won't be at low speeds for long


    40. 04-24-2005 11:19 AM #25
      Rolling resistance can actually have a big effect on fuel economy. There's a reason why Hondas, VWs and other cars come with Michelin MXV$ Energy tires or the like - studies have shown that fuel economy can be increased by 3-5 or more % by using these tires. It's an easy way for car manufactures to meet mileage requirements.

      I recently bought a new set of tires and instead of the normal low rolling resistance commuting-type tire I usually get, I decided to get some sportier, more sticky Bridgestones (Potenza G009s, which aren't even that sporty). My fuel economy over the first 2k miles with the Potenzas was almost 2 MPG less than with the old tires. I used to be able to make 4 commutes to work with about 30-40 miles to spare, but recently I've had to fill up after 3 because I would be running on fumes during the latter part of the 4th commute.

      Luckily Bridgestone has a 30-day test drive program where if you're not happy with the tires for any reason, you can return them for a full refund. I walked into Curry's, told them I didn't like Potenzas and walked out with a set of Michelin MXV$ Plus tires. All I had to do was pay the difference in tire price.

      Gary


    41. 04-24-2005 12:12 PM #26
      That is interesting Gary. Obviously, in the problem that I solved, the coefficient of tire friction was a fixed value that my Physics book gave me as an average coefficient of friction (likely based on a hard, economical tire). I'm sure this coefficient changes with tire material and brand. Air pressure and width no doubt has an effect as well. My doubts came from the fact that the total rolling friction (regardless of a small change in the tire coefficient of friction (aka moving to stickier tires)) accounted for a very small amount of the total power output needed by the car. Obviously, it takes gasoline to make that power we all crave, but I just assumed a relatively small amount of power needed for stickier tires would not consume a noticeable amount of gasoline.

      Then I started to mathematically figure out how much power the stickier tires would consume...but I ended up making a tee time instead

      Since I am on my way out the door, I will just say that it is hard to compare numbers and theory against you and your driving machine


    42. 04-24-2005 12:38 PM #27
      LOL.

      I've been doing a lot of reading on rolling resistance lately (the 2 MPG decrease was driving me nuts!) and have read in many places that rolling resistance can account for something like 10-30% of the power needed to keep the car moving (depends greatly on the car). Tires like the MXV4s, through tread design, sidewall stiffness, tire pressure and tread compound (more silica, less carbon black) can reduce rolling resistance as much as 60%. That is obviously a HUGE change when factoring how much of the total engine output is sucked up by rolling resistance.

      On a less scientific note, I noticed a HUGE difference with the MXV4s compared with the previous Potenzas. When accelerating, the engine felt like it was not working as hard and oddly enough, like the tires were not "sticking" to the road as much. Also, when on the highway and letting off the gas completely, the cars speed does not drop nearly as quickly with the MXV4s as it did with the Potenzas. I used to be able to use more engine braking when navigating sop-and-go rush hour traffic, but now find myslef having to use the brakes more in order to keep frem rolling into the car in front of me.

      Gary


    43. 05-11-2011 01:10 AM #28
      I cut the wire to my day time driving lights, (less load for the generator) i did not record if that made a difference in my gas mileage.

      I grive a 24v vr6 i get 25 mpg beating on it and 28mpg driving nice in the city, Got 32mpg on hwy.

    44. Member vwjon21's Avatar
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      05-11-2011 04:12 PM #29
      what i have learned is the key is loss weight because the less weight the less drag on the motor (power to weight ratio)

    45. Member ogvr6's Avatar
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      05-11-2011 06:19 PM #30
      a dusty thread........but still factual ....
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