2.0 TDI 150 Significant Drop in MPG
Discussion
Morning All,
Apologies if this has been covered off in other posts but my newly acquired Passat's mpg has dropped by around 25% over the past few weeks and I'm just curious as to whether anyone on here has had similar issues and if so, what the cause was.
The car's a 2016 Passat 2.0TDI 150 manual with 49k on it and a full service history. I picked it up 5 weeks ago where the long term average on the trip computer was reading 54mpg. A 120 mile drive home from the dealers delivered 58mpg and journeys over the next week or gave 55mpg+ but over the past 3 weeks or so economy seems to have nose dived to the point where I'm struggling to get anywhere near 45mpg. A 50 mile run earlier this week with cruise control set at 72mph returned 42mpg according to the trip computer, which is pretty grim for something that I'd expect to deliver close to 60mpg on that type of journey.
As I'm currently working from home mileage is minimal, however all journeys I've made have been 40+ miles on the motorway at <75mph so are pretty much what the car is made for. I've had similar sized diesels for the past 300k miles so have a pretty good handle on how to drive them economically.
Has anyone had any similar experiences with this engine? The fact this mpg was in the high 50's for the first week or so suggests to me that it's more of an issue with the car rather than high expectations of fuel economy but I can't pinpoint what will have caused the sudden drop when my driving style / journey type hasn't changed and the car still seems to drive perfectly.
I've got it booked in with VW in the new year to have a look and carry out a service (last service was 10k miles ago where fuel filter was done) but it'd be good to have ideas as to what it could potentially be prior to going in there.
Thanks in advance.
Apologies if this has been covered off in other posts but my newly acquired Passat's mpg has dropped by around 25% over the past few weeks and I'm just curious as to whether anyone on here has had similar issues and if so, what the cause was.
The car's a 2016 Passat 2.0TDI 150 manual with 49k on it and a full service history. I picked it up 5 weeks ago where the long term average on the trip computer was reading 54mpg. A 120 mile drive home from the dealers delivered 58mpg and journeys over the next week or gave 55mpg+ but over the past 3 weeks or so economy seems to have nose dived to the point where I'm struggling to get anywhere near 45mpg. A 50 mile run earlier this week with cruise control set at 72mph returned 42mpg according to the trip computer, which is pretty grim for something that I'd expect to deliver close to 60mpg on that type of journey.
As I'm currently working from home mileage is minimal, however all journeys I've made have been 40+ miles on the motorway at <75mph so are pretty much what the car is made for. I've had similar sized diesels for the past 300k miles so have a pretty good handle on how to drive them economically.
Has anyone had any similar experiences with this engine? The fact this mpg was in the high 50's for the first week or so suggests to me that it's more of an issue with the car rather than high expectations of fuel economy but I can't pinpoint what will have caused the sudden drop when my driving style / journey type hasn't changed and the car still seems to drive perfectly.
I've got it booked in with VW in the new year to have a look and carry out a service (last service was 10k miles ago where fuel filter was done) but it'd be good to have ideas as to what it could potentially be prior to going in there.
Thanks in advance.
Time of year? The cold really affects a diesel. As said, shorter journeys because of lockdown and wfh. That said, an Audi I had years ago did similar, but the. I also go the wife of diesel in the cabin a few days later. The fuel filter was leaking. Crappy dealer ‘fixed’ it, but it continued. They had a second go at it and all was good.
How do you drive?
I drive some diesels to work and I drive them exactly like petrols I.e. I redline them at times. If you are anywhere near this the engine won't like it for mpg...
To get the best mpg out of diesel, to me it feels like you almost have to labour the engine in all gears.
I drive some diesels to work and I drive them exactly like petrols I.e. I redline them at times. If you are anywhere near this the engine won't like it for mpg...
To get the best mpg out of diesel, to me it feels like you almost have to labour the engine in all gears.
Thanks for the reply - appreciate it.
I've only had the car for 1,000 miles or so but within that was a 250 mile round trip to Birmingham where it struggled to crack 50mpg sat at 70mph and with countless sections of 50mph roadworks. The 180k mile Mk4 Mondeo I had before this that was hardly the most economical of diesels (48mpg combined book figure vs 65mpg for the Passat) would indicate 50mpg+ on the same journey with roof bars on it.
The fact that I was getting 55mpg+ with ease during the first week or so and I haven't changed my journey type since doesn't point to driving style or anything like that vs the previous owner.
It came with a full tank of fuel and the drop in mpg started whilst still on the original tank so I'm not sure how much it can be linked to bad fuel. I did chuck Tesco diesel in it when I filled up but mpg had already trailed off by that point. Will go with something better next time to see if there's any impact though. Temperature hasn't dropped too significantly to when I picked it up 5 weeks back either.
Not trying to dismiss any of your suggestions by any means as they're all ones that I've run through but none of them seem to fit with a 20-25% reduction in economy that seemed to happen almost overnight.
I've only had the car for 1,000 miles or so but within that was a 250 mile round trip to Birmingham where it struggled to crack 50mpg sat at 70mph and with countless sections of 50mph roadworks. The 180k mile Mk4 Mondeo I had before this that was hardly the most economical of diesels (48mpg combined book figure vs 65mpg for the Passat) would indicate 50mpg+ on the same journey with roof bars on it.
The fact that I was getting 55mpg+ with ease during the first week or so and I haven't changed my journey type since doesn't point to driving style or anything like that vs the previous owner.
It came with a full tank of fuel and the drop in mpg started whilst still on the original tank so I'm not sure how much it can be linked to bad fuel. I did chuck Tesco diesel in it when I filled up but mpg had already trailed off by that point. Will go with something better next time to see if there's any impact though. Temperature hasn't dropped too significantly to when I picked it up 5 weeks back either.
Not trying to dismiss any of your suggestions by any means as they're all ones that I've run through but none of them seem to fit with a 20-25% reduction in economy that seemed to happen almost overnight.
Sorry - didn't expect 5 replies in the time it took to reply to the first!
As above, I've owned similar diesels (2.0 and 2.2) for the past 300k miles and certainly over the past few years have focused more on economy so had a decent handle on how to get good mpg out of them.
I avoid short journeys where I can and traffic on the road is minimal now anyway so all journeys are at a steady 70-75mph on cruise.
I realise outside temperature will have an impact by a few mpg but nothing like this level.
Fuel filter was replaced at last service at 40k miles (according to service book) at a VAG specialist so I'd hope that it's a decent filter in there.
As above, I've owned similar diesels (2.0 and 2.2) for the past 300k miles and certainly over the past few years have focused more on economy so had a decent handle on how to get good mpg out of them.
I avoid short journeys where I can and traffic on the road is minimal now anyway so all journeys are at a steady 70-75mph on cruise.
I realise outside temperature will have an impact by a few mpg but nothing like this level.
Fuel filter was replaced at last service at 40k miles (according to service book) at a VAG specialist so I'd hope that it's a decent filter in there.
Edited by CTS86 on Saturday 12th December 10:42
I've got a MK6 Golf GT with the same EA189 engine, albeit 140ps. I can get as high as 68mpg according to the trip if everything is bang on ideal (low traffic, temp, etc). My actual reading measured at the pumps is between 48 and 52mpg, usually in the 50s with the lower traffic levels we have now.
The Golf is obviously a lighter car though, and I always use V-Power diesel. Many people have an opinion on this, but in my mind it's worth the extra. Never get a DPF light on and the only "diesel related" issue I've had is a throttle body that needed cleaning, and I've took the car from 42k to nearly 108k now.
Maybe there is a blockage somewhere? I'd try a few tanks of V-Power and see how you go. I assume you've checked the obvious things like tyre pressures and if anything is binding.
The Golf is obviously a lighter car though, and I always use V-Power diesel. Many people have an opinion on this, but in my mind it's worth the extra. Never get a DPF light on and the only "diesel related" issue I've had is a throttle body that needed cleaning, and I've took the car from 42k to nearly 108k now.
Maybe there is a blockage somewhere? I'd try a few tanks of V-Power and see how you go. I assume you've checked the obvious things like tyre pressures and if anything is binding.
A couple of things I'd try... e brake make sure rear brakes aren't sticking/binding as mentioned above. Do you have a roof rack? Injector leak? What fuel are you running? Do all lights light on the dashboard on start up (i.e. non failing to light), use an injector cleaner supplement from eurocarparts (cheap with offer). When was the last oil/filter change?
Has it had the VW emissions fix?
Has it had the VW emissions fix?
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