MPG Underperformance

Discussion in 'VW Jetta hybrid forum' started by Bossless, Aug 3, 2014.

  1. Bossless

    Bossless Member

    I think the mpg sweet spot for this car is around 50 mph steady plus or minus 3 mph. Before the recall I could get 50 mpg plus under these conditions. These are not normal driving conditions for most drivers, nor are the EPA ratings based on these conditions.
  2. I800C0LLECT

    I800C0LLECT Member

    I completely agree. Once you get above 70mph the mileage beings to drop very quickly. Stop and go hurts me much more since I moved to the 17" Goals. I've seen reports of them being 20lbs or even 22lbs per wheel. With the original 16" wheels I could easily get moving off the battery. It's not so easy with the Goals though.
  3. fgbrault

    fgbrault Member

    Last edited: Aug 13, 2014
  4. I800C0LLECT

    I800C0LLECT Member

    That is interesting...

    From the dyno testing thread linked to argonne TTRDC...

    The SC03 Cycle achieved 32mpg

    The US06 Cycle achieved 35mpg
  5. Bossless

    Bossless Member

    42/45/48 are the EPA mpg ratings VW advertises for the Jetta hybrid. Based on my real world driving experience I would say that at best the mpg ratings should be 38/41/44. Anyone agree or disagree?
  6. cdrussell

    cdrussell Member

    I haven't studied the details of how the EPA mpg ratings are measured, but for hybrids, I think the actual mileage you will get is very dependent on the type of driving you do. If your driving doesn't match the way the EPA measures it, your mileage could be way different. My typical driving must be in the sweet spot because I've been averaging about 45 mpg per tank over the spring/summer/fall. But over the last four days I've been doing a lot of highway driving with four people in the car and have only been getting about 37 mpg. I can't seem to get anywhere near the 48 mpg rating while driving on the highway but overall my mileage has been good.
  7. I800C0LLECT

    I800C0LLECT Member

    I think the cycles I quoted are more representative of how people typically drive. I have noticed that I accelerate aggressively while in traffic to keep so I'm not "that guy". When I have more time to get up to speed I can achieve 42mpg even on a short run for milk.
  8. Bossless

    Bossless Member

    My experience is that I have lost about 9% in fuel efficiency since the transmission safety recall. Also, it appears that I will now need to change the transmission fluid every 40K miles at about $300 a pop, whereas no change was required for the 7-speed DSG when it had synthetic fluid. I would be curious to know if the 2014 user maintenance manual calls for the fluid to be changed

    I really like this car but the economic picture is turning out to be a looser.
  9. I800C0LLECT

    I800C0LLECT Member

    I never read any articles stating that it needed to be changed routinely after the recall. It's hard to know if you have the latest transmission firmware or what exactly changed due to ignorance/user error.

    Anyways, the dq200 is a dry clutch. Why do you have to change gear box fluid every 40k?
  10. I800C0LLECT

    I800C0LLECT Member

    I'll disagree. I think in your situation mine would be similar but I've achieved 51 in a different scenario from my daily driving.

    My is usually over-estimating in the upper 30's and under-estimating once it gets into mid 40's. It only averaged 46 when I hit that 51mpg tank and I've hit mid 50's several times on a drive home when traffic limits interstate speeds between 40 and 50mph.

    There's an article on the net somewhere stating 60mpg when hyper-miling I thought? Even the links I sent on the dynamometer/epa fuel efficiency backs that up...if you cherry pick.

    I think the real issue is that the vehicle is designed with a much larger performance envelope vs a prius. The problem is that nobody drives their jetta as conservatively as what the prius forces on us.
  11. Bossless

    Bossless Member

    That is what is required for the 6-speed DSG which uses non-synthetic fluid, however it does have a wet clutch. I talked to VW care and they recommended a change between 40 and 50K. I pointed out that the maintenance manual does not require that. They said they would make a note about that. Some dealers are recommending a change on the DSG 7-speed at 40K also. If changing to non-synthetic fluid makes a difference in maintenance, VW needs to specify it.

    BTW, the transmission recall was done a second time under VW corporate supervision on my car to make sure it was done properly and is up to date.
  12. I800C0LLECT

    I800C0LLECT Member

    My previous jetta TDI had a dq250 which had 6 speed gear box and required fluid change.

    But the 7 speed gear box in the hybrid shouldn't require any changes all even after recall. The recall was due to the specific fluid composition used that would eventually cause a short in the electrical board due to corrosion. The new mineral fluid shouldn't cause any corrosion/short out the pcb.

    It's not the greatest explanation but you can find an in depth article on the web that provides details on it all. I wouldn't trust the dealership that suggests you to change the gear box fluid every 40k. It wasn't designed to be changed regularly and I think requires special gasket/parts that aren't available outside the recall
  13. I800C0LLECT

    I800C0LLECT Member

    This should help....

    http://www.sgcarmart.com/news/writeup.php?AID=180

    SGCM: What is the technical issue behind the recall?

    VW: Sulphur in the gear oil and an inorganic heat stabiliser in the plastic parts (iodine) of the mechatronic unit can cause metallic surfaces to be attacked and to suffer from electrolytic corrosion, in connection with high air humidity and high outside temperatures. Conducting particles can then settle between the circuit paths of the control unit and could cause a short circuit.

    SGCM: Is it true that only the seven-speed gearbox has been affected?

    VW:
    The subject of the voluntary recall is the DQ200 seven-speed DSG gearbox. Volkswagen also produces the DQ250 six-speed DSG and DQ500 seven-speed DSG which are not affected by this voluntary recall.

    SGCM:
    What will be the scope of work done?

    VW:
    As part of the voluntary recall, Volkswagen Singapore will replace the gearbox mechatronics on affected vehicles at zero cost to the customer. The work will take around three hours per car to complete.​
  14. Bossless

    Bossless Member

    Dealers want to make money so I can see how they would want to change the fluid. However, I was surprised that VW care would support that position. One thing that bugs me is there must have been a reason for them to go to the synthetic fluid in the first place. Now that they had to go back to the mineral based fluid to solve the corrosion problem, what has been given up? Fuel milage? Use longevity?

    My position is that the car I have is no longer the car I bought because of the post production transmission mod. I now have a different fluid and a different TCM software protocol. I have documented a 9% efficiency loss after the recall and now may be faced with additional maintenance expense for transmission fluid changes. (Strange that VW Care will not verbally specify no fluid change even though the manual indicates no change. And to my knowledge, the 2014 manual still does not specify a fluid change for this transmission.)

    Another interesting note. At about 18,000 miles I starting getting slight shudder at times on normal take off. After the fluid was changed, the shudder is gone as far as I can tell within the 274 miles I have driven since the change (This was the second fluid change within 18,600 miles.)
  15. I800C0LLECT

    I800C0LLECT Member

    I can certainly understand the frustration but the synthetic oil was new and use mineral oil is not. The recall reverses the decision to use a synthetic oil. They used synthetic oil for less than a year before reverting back to the standard. I still wouldn't trust VW customer service or dealership statements about routine gearbox fluid changes. The gearbox is a closed system without a filter and that is specifically why it doesn't require routine service. VW did not require any routine maintenance for any other DQ200 prior to switching to synthetic oil. They haven't changed their stance since they moved all DQ200's back to mineral oil.

    I'd like to know if your transmission and ECU are the most current tunes. I think APR told me that they'd flash my dq200 if I wanted
  16. Bossless

    Bossless Member


    Two dealers have told me that my car is up to date.

    My point is that VW used the synthetic oil for a reason. It is more expensive than mineral based oil, so there must have been some benefit to use it--performance, efficiency, etc. Now, that benefit has been taken away. That, along with the TCM software update, I think, is responsible for my 9% mpg loss.
  17. I800C0LLECT

    I800C0LLECT Member

    I've seen hybrid owners complaining of lower FE after the recall but I still don't think mineral oil is adding THAT much to parasitic loss. As long as they're using a quality mineral oil I don't see how it's viscosity could be vastly different from synthetic...let alone, so much thicker that it's contributing to almost 10% loss in FE. It's pretty close to hydraulic fluid. My presumption is that the TCM software is the issue. Remember, they did a recall/update to the TCM that contributed to an almost 10% better FE.

    I'm not trying to take away from your claims, I just don't see any reason to routinely change the gear box fluid. I still can't find any other regions or suggestions from VW that doing so is beneficial.

    My own experience is that I've had to literally write down TB's, part #'s, or software versions for dealerships and techs after being told "it's up to date!!". This has happened at 3 different dealerships. I suspect the root of confusion is in the manner that VW supports the mechanics. I had 3 appointments just to update the bluetooth module in my vehicle(Passat). They were adament that I didn't know what I was talking about and displayed their software program that didn't display any required updates for my vehicle. After I made them search for the proper TB and software version they scratched their heads and couldn't figure out why that never surfaced...

    Bottom line. I don't trust the service technicians. There is a problem with your vehicle and I whole heartedly suspect it's the TCM version. Use vag-com to see what version you have and do some research? I really need to buy one myself
  18. Bossless

    Bossless Member

    My understanding is that a synthetic oil with the same viscosity as a mineral based oil has a lower coefficient of friction and is more efficient. However, I agree that it would not be enough to be responsible for my total FE loss. Supposedly, a VW Corporate rep was on site to monitor the recall redo. That was part of the agreement with VW to ensure that it was done right. I think I will press them again on the update to see if I can find any holes in what they did. They will probably tell me it was a readout code from their diagnostic computer. Do you know if there is any TB that I can ask them to review to ensure that they are correct? Like you I don't really trust them. I've had them tell me (not this dealer but another one) that they checked the transmission fluid level, which cannot be done. They also told me that the update to the TCM was done before I took delivery of the car and did not have to be done as part of the recall. My understanding is that was an overall software optimization to improve FE that was not connected with the recall.

    So, I am not sure what is going on here, but I have a lot of suspicions. If you can give me any specifics on the software updates, it would be most helpful.
  19. I800C0LLECT

    I800C0LLECT Member

  20. Bossless

    Bossless Member

    Thanks for the link. Lot of information there. I'll be wading through it to see what I can learn as I have time.

    I questioned my dealer about the TCM software being up to date. He said they connected up the system and told it to do an update and a message came back saying it was already up-to-date. So far I have had the recall done twice, taken my car back three times trying to solve the loss of mpg with no positive results.

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