2019 Leon FR 2.0TDI 150 - Fuel Economy Worsening
Discussion
I have a 2019 Seat Leon FR 2.0 TDI 150hp model. The fuel economy is gradually getting worse, and I can’t understand why. I’m using the same fuel, doing the same mixed type of driving with the same driving style. I’ve tried it on the different eco/sport drive modes and none of them appear to have any effect.
I’m a bit OCD with things, and only ever fill the tank, this allows me to log mileage, (actual) fuel economy and distance travelled per tank. When I first got the car, it would do 550+ miles to a tank, and now struggles to exceed 400. The attached graph shows the decline in fuel economy on the red average plot. Each point is the mpg for each fill. I keep expecting it will level out but it continues to trend down. I filled up today and registered the worst I’ve seen over a tank, 40.4mpg. I’m not expecting to see the 56/57mpg I saw in the first few weeks of my ownership because that was almost all entirely motorway mileage, but I would expect that it would do more than 40mpg.
The car has a service plan with Seat so its servicing is all up to date. Serviced at the end of January, approx 3200 miles ago.
Any suggestions?
I’m a bit OCD with things, and only ever fill the tank, this allows me to log mileage, (actual) fuel economy and distance travelled per tank. When I first got the car, it would do 550+ miles to a tank, and now struggles to exceed 400. The attached graph shows the decline in fuel economy on the red average plot. Each point is the mpg for each fill. I keep expecting it will level out but it continues to trend down. I filled up today and registered the worst I’ve seen over a tank, 40.4mpg. I’m not expecting to see the 56/57mpg I saw in the first few weeks of my ownership because that was almost all entirely motorway mileage, but I would expect that it would do more than 40mpg.
The car has a service plan with Seat so its servicing is all up to date. Serviced at the end of January, approx 3200 miles ago.
Any suggestions?
Drive Blind said:
Brake(s) binding ?
Another thing to look at is the engine getting properly up to temp? Thermostat or cooling sensor issues could mean the car is running cold and will overfuel.
Air and fuel filters replaced ?
Temperature gauge always reads normal, 90°. I’m aware that there can be a variation of around 20° either side on the VAG stuff and gauge still reads 90. Will need to update my VCDS to get some live data. Another thing to look at is the engine getting properly up to temp? Thermostat or cooling sensor issues could mean the car is running cold and will overfuel.
Air and fuel filters replaced ?
Nozzasti said:
silly question, are you using the air con at all? I have a similar car (150bhp 1.5 petrol version) and my mpg suffers when I'm using the air con, I do have dsg which doesn't help though.
I am, and it’s always on, always has been on all of my cars, and none of them are showing a similar downward trend in mpg. I’ve tested in the past through periods of AC on and off and in real world averaged figures rather than the cars in built display the difference is usually negligible. ReverendCounter said:
Failing coolant temp sensors can cause some ECUs to think they need to permanently run rich, but I have no experience with your particular car.
It’s something I’ve considered, and I have encountered it before on the Mk4 platform golf diesel models. As mentioned earlier in this post, my VCDS doesn’t support a car as new as this and will need replaced to do so. It’s still under warranty so hopefully after my email to them today the dealer agree to have it back for some diagnostics. I posted here more in the hope that someone said “oh yes, my exact same car did the exact same thing, it was this specific fault. “ however unlikely that may have been.
I bought something new with manufacturer warranty because I was tired of tinkering or having to think about anything. That’ll teach me!
I wondered about DPF Regens, but no idea if/when it’s doing them. Surely it would have to be pretty frequent to cause this sort of drop in mpg?
It’s a manual, but it has Sport, Eco or Individual drive modes. A gimmick I’m sure, I’ve never been able to tell the difference between them, other than a decreased throttle response in eco mode, and it’s had no effect on fuel economy.
It’s a manual, but it has Sport, Eco or Individual drive modes. A gimmick I’m sure, I’ve never been able to tell the difference between them, other than a decreased throttle response in eco mode, and it’s had no effect on fuel economy.
John3l said:
I wondered about DPF Regens, but no idea if/when it’s doing them. Surely it would have to be pretty frequent to cause this sort of drop in mpg?
It’s a manual, but it has Sport, Eco or Individual drive modes. A gimmick I’m sure, I’ve never been able to tell the difference between them, other than a decreased throttle response in eco mode, and it’s had no effect on fuel economy.
Revs sit higher when doing a DPF regen, and is always nagging you to be in a lower gear then you expect.It’s a manual, but it has Sport, Eco or Individual drive modes. A gimmick I’m sure, I’ve never been able to tell the difference between them, other than a decreased throttle response in eco mode, and it’s had no effect on fuel economy.
I wondered about DSG as those have an additional thermostat for the DSG cooler which sticks open,
Wife has same engine in a Tiguan, although hers is DSG (and 4Motion). Had it since new for 8yrs and it's done about 45K. She pretty well only uses it locally (semi-rural) and uses a tank of fuel per month. I spreadsheet the fuel consumption (as we had a car where it dropped 25% and no-one believed us) and it's remarkably steady around 40MPG (calculated) all year round unless it's been on a long run when it'll be higher. Display shows long term average 42. Trip average will show 45 on a reasonable run and 50 on a long run, but they're rare events.
I reckon it regens somewhere between 2-300 miles but it's very hard to pick up it's doing it unless you stop and get out of the car and hear the fan roaring. Stop/start doesn't work during a regen but we switch that off anyway. Supposedly it regens less on Shell VPower but it just became too expensive. Generally fill now with Costco Super stuff. Same MPG - I think the engine is a little smoother on Costco fuel.
How's the AdBlue consumption - has that increased too? I think it's used in ratio to diesel used. Ours is using approx a litre every 600 miles (approx).
Wife has same engine in a Tiguan, although hers is DSG (and 4Motion). Had it since new for 8yrs and it's done about 45K. She pretty well only uses it locally (semi-rural) and uses a tank of fuel per month. I spreadsheet the fuel consumption (as we had a car where it dropped 25% and no-one believed us) and it's remarkably steady around 40MPG (calculated) all year round unless it's been on a long run when it'll be higher. Display shows long term average 42. Trip average will show 45 on a reasonable run and 50 on a long run, but they're rare events.
I reckon it regens somewhere between 2-300 miles but it's very hard to pick up it's doing it unless you stop and get out of the car and hear the fan roaring. Stop/start doesn't work during a regen but we switch that off anyway. Supposedly it regens less on Shell VPower but it just became too expensive. Generally fill now with Costco Super stuff. Same MPG - I think the engine is a little smoother on Costco fuel.
How's the AdBlue consumption - has that increased too? I think it's used in ratio to diesel used. Ours is using approx a litre every 600 miles (approx).
I have a Skoda with the 150 2.0 TDi and one of the two secondary water pumps failed (one which circulates coolant around the charge cooler). When that was replaced the mpg shot up by about 10 mpg. Granted mine put a warning light on when the pump failed but I think it was a slow failure i.e. had to get properly knackered before it put the light on. Something to consider.
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