Horrible Fuel Economy - '07 GS 350 AWD - 13L/100KM (18MPG)
12-24-15, 05:39 AM
#16
It's really odd that this keeps happening on this site. I post a post and it either gets cut off later or parts of the post are removed.
I can't get higher than 14 MPG for the past few days.
I can't get higher than 14 MPG for the past few days.
12-24-15, 09:55 AM
#18
Lead Lap
I've been hovering right around 14 MPG with my 460 the past few weeks. Had very limited freeway driving lately, plus WA is packed with hills and stop and go traffic, so that could be adding to it. Probably partially the winter blend gas as well. You're definitely not alone on this 
12-24-15, 12:22 PM
#19
I've been hovering right around 14 MPG with my 460 the past few weeks. Had very limited freeway driving lately, plus WA is packed with hills and stop and go traffic, so that could be adding to it. Probably partially the winter blend gas as well. You're definitely not alone on this
12-27-15, 01:19 AM
#20
Got the same car 07 GS AWD stock with cooper tires RS3 - A.... My fuel ecnomy has been around 14-18 too didnt change the plugs need to maintenance on filter tho... not sure which one haha... How would you guys clean the filters? I'm not entirely sure but I kind of noticed that when i use 89 i get more MPG rather than 93 which is kinda weird... but they didnt take the same route but should have been I'll conclude more tests further!
12-27-15, 05:39 AM
#21
Pole Position
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I'm with TRD_Power, hovering around 14mpg. It does seem to reset for each time I fill up on gas, so if I drive it hard after a fill up... drops to 9mpg. If I baby the throttle it climbs back up to 15-16mpg. I've posted a picture on a different thread heading towards Las Vegas and busted a 26mpg running under 75mph. Its a heavy sedan naturally aspirated... I can imagine we can save more if it was turbocharged. lol
12-27-15, 05:50 AM
#22
Driver School Candidate
My 08 Gs350 is 2wd. But I'm currently in the middle of a tank, mostly highway miles, flat terrain, non blended premium gas. 29.5 mpg so far. Driving around town does drop it quickly though but still will maintain 23-24 mpg. I'm in Oklahoma.
12-27-15, 01:53 PM
#24
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Hi all:
Hoping for some input.
Purchased an '07 GS 350 AWD in June. For first few months the fuel economy was wonderful (about 10-10.5L/100KM or 23MPG). Suddenly, it seemed like overnight it went down to about 13L/100KM or 18MPG.
I noticed this big change when I received a 'Low Oil' warning on my dashboard about 5000KM into my first oil change (which was right after I purchased the car). I changed from conventional to synthetic and have since then read about the unfortunate burning oil issue.
Anyways, spark plugs were replaced by previous owner in December 2014. I've tried the STP fuel cleaner. New engine air filter. Tires are new and properly inflated. None of this made a difference.
Has anyone else had this drastic drop in fuel economy and been able to pinpoint the culprit? My driving habits haven't changed so I'm just looking for some advice on how to get those numbers back.
Side note, is there a way to reset the fuel economy to start from scratch? My next step will probably be to do manual measures to make sure the numbers are accurate.
Help!
Hoping for some input.
Purchased an '07 GS 350 AWD in June. For first few months the fuel economy was wonderful (about 10-10.5L/100KM or 23MPG). Suddenly, it seemed like overnight it went down to about 13L/100KM or 18MPG.
I noticed this big change when I received a 'Low Oil' warning on my dashboard about 5000KM into my first oil change (which was right after I purchased the car). I changed from conventional to synthetic and have since then read about the unfortunate burning oil issue.
Anyways, spark plugs were replaced by previous owner in December 2014. I've tried the STP fuel cleaner. New engine air filter. Tires are new and properly inflated. None of this made a difference.
Has anyone else had this drastic drop in fuel economy and been able to pinpoint the culprit? My driving habits haven't changed so I'm just looking for some advice on how to get those numbers back.
Side note, is there a way to reset the fuel economy to start from scratch? My next step will probably be to do manual measures to make sure the numbers are accurate.
Help!
12-29-15, 08:32 AM
#25
Lead Lap
Jumped on the freeway a bit this weekend, and now I'm getting between 17 and 19 mpg. It's been quite a bit cooler this winter than last here in WA, plus I'm not parking in a garage anymore, so that could add to the richness of the fuel, but not positive. Anyways, if I'm sticking close to 20 MPG with the traffic and hilly roads here, then I'm a happy camper.
12-29-15, 11:14 AM
#26
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50/50 mix of road and city with my 07 GS350 AWD is producing 24.5 - 25mpg. Honestly, if my car started doing what your is and I couldn't find a solution, I'd be pulling my hair out. That's horrible and you have every right to be concerned. Do us a favor and keep up posted, I am very curious what you find.
12-30-15, 05:16 PM
#27
Well mine steadily went back up towards 18 then dropped back to 13 pretty abruptly. It's been about 70° here for the past months in NC (yeah, that's our winter now). It's all city driving but I have been babying the gas pedal. I'm pretty convinced off of articles by well known authors and the timing that putting in the STP fuel system treatment threw the computer for a loop and it doesn't know what to read. The STP treatment was not good by any means or a solution to my problem of getting 18 mpg instead of 20+ mpg. I'll clean out the tank and refill and try again.
01-03-16, 01:23 PM
#28
Driver
Thread Starter
No real updates. I recently changed work locations so now I'm doing predominantly highway driving... I'm right now averaging about 11-11.5L/100KM (approx. 20.5-21.5MPG) with about 80% highway. I still miss when I first picked up the car in the summer and I was doing about 8.5L/100KM.
Either with city driving or highway driving, it seems to be an all around jump of about +3L/100KM.
I still have to take it in for a proper inspection or play around with it.. unfortunately it's starting to finally get cold up here in Toronto.
Yeah, that's what I used to get initially until fuel economy plummeted in September or so. Miss those days 
Either with city driving or highway driving, it seems to be an all around jump of about +3L/100KM.
I still have to take it in for a proper inspection or play around with it.. unfortunately it's starting to finally get cold up here in Toronto.
50/50 mix of road and city with my 07 GS350 AWD is producing 24.5 - 25mpg. Honestly, if my car started doing what your is and I couldn't find a solution, I'd be pulling my hair out. That's horrible and you have every right to be concerned. Do us a favor and keep up posted, I am very curious what you find.
01-25-16, 01:03 PM
#29
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What Happened?
I was having a problem at startup, where the engine sounded flooded for a few moments and several times it took 3 tries to start the car (all at cold starts). The dealership had the car for 2 weeks and finally told me they replaced the fuel injectors because of a leak. Now I have the car back, and the problem is still there; but now I'm getting FIVE LESS MPG. Really? No other changes. I'm livid. Went from 21.3-21.8 around town to 16-16.5.
Last edited by pezfooty; 01-25-16 at 01:04 PM. Reason: add on thought
05-25-16, 09:31 PM
#30
Driver
Thread Starter
May 2016 Update
Just an update... Finally got around to cleaning the MAF Sensor (never realized it was literally a 10 minute procedure). No improvement in fuel economy. Also threw in a can of seafoam into fuel tank (no real reason except that I heard it helps lol). No improvement.
To be fair though, I've prob driven 100KM or so since cleaning the sensor so I'll wait to go through another tank of gas before actually gauging if it had an impact.
My buddy was saying to try a tank of regular gas (87) since the previous owner was using that. Any logic behind this?
To be fair though, I've prob driven 100KM or so since cleaning the sensor so I'll wait to go through another tank of gas before actually gauging if it had an impact.
My buddy was saying to try a tank of regular gas (87) since the previous owner was using that. Any logic behind this?
