Poor Fuel Economy, Strong Exhaust Smell
Thread Starter
Super Member
Joined: Feb 2013
Posts: 533
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From: Pennsylvania
2021 GLE450
Poor Fuel Economy, Strong Exhaust Smell
We just completed a 2,000-mile road trip. In addition to the normal glitches I've come to expect from our GLE, we observed awful fuel economy. The drive away from home returned 25.3 mpg, which is exactly what we expect on a primarily highway winter road trip. On the return drive we managed just 20.8, however. Same roads, same speeds. The temps were lower when we started the return 2-day drive, and we had a bit of a headwind, but those weather conditions wouldn't account for such a dramatic drop. After pulling in the garage we noticed an incredibly strong exhaust smell -- not a sulfur odor, but what you'd expect when a car is running rich. The car is not smoking, and it seems to be running ok. The DI clatter, while not exactly pleasant, doesn't sound any different to me.
I called the dealer to set an appointment, and the scheduler said it sounds like a known issue with a fuel line. He's not a tech, so he couldn't elaborate, but he insisted it's safe to drive. I don't recall seeing any threads here on the topic, but I'm curious if anybody knows what he was talking about. The first available appointment is 1/31, and my wife is already uncomfortable driving it for weeks without a formal diagnosis. We'd appreciate any input.
I called the dealer to set an appointment, and the scheduler said it sounds like a known issue with a fuel line. He's not a tech, so he couldn't elaborate, but he insisted it's safe to drive. I don't recall seeing any threads here on the topic, but I'm curious if anybody knows what he was talking about. The first available appointment is 1/31, and my wife is already uncomfortable driving it for weeks without a formal diagnosis. We'd appreciate any input.
Last edited by HotRodW; Dec 24, 2024 at 12:47 PM.
Super Member
Joined: Mar 2022
Posts: 556
Likes: 197
From: NJ
2022 GLE 450
The only fuel related post I can remember, was that of a fuel pump recall over a year ago. In fact, you, @HotRodW , posted about it on 7/3/2023.
https://mbworld.org/forums/gle-class...mp-recall.html
Did you ever have it replaced?
https://mbworld.org/forums/gle-class...mp-recall.html
Did you ever have it replaced?
Last edited by TonyF61; Dec 24, 2024 at 01:46 PM.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 533
Likes: 240
From: Pennsylvania
2021 GLE450
Thread Starter
Super Member
Joined: Feb 2013
Posts: 533
Likes: 240
From: Pennsylvania
2021 GLE450
The only fuel related post I can remember, was that of a fuel pump recall over a year ago. In fact, you, @HotRodW , posted about it on 7/3/2023.
https://mbworld.org/forums/gle-class...mp-recall.html
Did you ever have it replaced?
https://mbworld.org/forums/gle-class...mp-recall.html
Did you ever have it replaced?
Last edited by HotRodW; Dec 24, 2024 at 03:15 PM.
Super Member
Joined: Mar 2022
Posts: 556
Likes: 197
From: NJ
2022 GLE 450
Have you checked your VIN lately? https://www.mbusa.com/en/recall Perhaps they expanded it. I seem to recall it was '21 to'23 GLE/GLS. Have you contacted the service dept?
Good Luck and Happy Holidays.
Good Luck and Happy Holidays.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 533
Likes: 240
From: Pennsylvania
2021 GLE450
Have you checked your VIN lately? https://www.mbusa.com/en/recall Perhaps they expanded it. I seem to recall it was '21 to'23 GLE/GLS. Have you contacted the service dept?
Good Luck and Happy Holidays.
Good Luck and Happy Holidays.
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Thread Starter
Super Member
Joined: Feb 2013
Posts: 533
Likes: 240
From: Pennsylvania
2021 GLE450
And the diagnosis ... probably a loose oil cap. Actually it wasn't just loose, it wasn't on at all. After initially blaming me for leaving the cap off, they ultimately took responsibility for leaving it off after my last service. They initially said the two issues couldn't be related, then they backtracked and said it was almost certainly the cause. I'm not convinced a missing oil cap will make the car run rich, and I'm surprised there were no codes thrown indicating a vacuum leak. I also expressed concerns about oil contamination, but I was assured that the oil is perfectly fine and couldn't possibly be contaminated. I'm to monitor fuel economy and return if it doesn't return to normal. Everything about this makes me uneasy.
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X214
Also out of curiosity, on the return portion of the trip, did you have additional load inside the car, say several 100 lbs worth of additional stuff that was not present in the outward journey ? Additional load in the car, obviously will cause a mileage hit.
Thread Starter
Super Member
Joined: Feb 2013
Posts: 533
Likes: 240
From: Pennsylvania
2021 GLE450
No. In fact we were running about 150 pounds lighter on the return trip when the mileage was at its worst. We have made this journey multiple times and the mileage has been very consistent. And there is no hiding the strong gasoline smell. Something was (and might still be) making the car run rich.
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Joined: Oct 2022
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X214
No. In fact we were running about 150 pounds lighter on the return trip when the mileage was at its worst. We have made this journey multiple times and the mileage has been very consistent. And there is no hiding the strong gasoline smell. Something was (and might still be) making the car run rich.
