Fuel efficiency: 10 mpg loss after service. What to check?
As part of that last service?
Could certainly explain the negative effects you're seeing. The EA189 service update causes much more frequent DPF regens, resulting in a drop in fuel economy.
No, it was over a year ago. Probably two years ago.
Since they replaced the brakes at the last service this was my first thought. But there's no indication that they're binding.
Soldato
Is it the same car?
If the drop in mpg were for short trip, temperature would cause some variance. But after the engine is up to optimum temperature, such variation should be small. Tyres the same. If about 3psi less than before, after 10-15 miles the temperature increasing, would increase its pressure about 3 psi, so unless greatly deflated, driving some serious distance shouldn't be enough for the 10mpg drop.
I would say it's the regen happening more often, the active one, which in my previous CX5 (2018) and the actual A Class (2019), keep the mpg about 20 to 25 mpg lower than the average, so even after some mileage in the same trip, the overall will be affected.
I would say it's the regen happening more often, the active one, which in my previous CX5 (2018) and the actual A Class (2019), keep the mpg about 20 to 25 mpg lower than the average, so even after some mileage in the same trip, the overall will be affected.
Over a 100 miles trip, one active regen can possibly impact the average mpg. At the moment, I'm achieving 60 odd miles, when the journey is 20 miles or longer. When is a shirt 10 miles, usually lows to mid 50s. But if a regen happens during one of those 10 miles trip, I would be luck do reach 40. But over 100 miles, should be ok to drop 2 or 3 mpg, or in the worst scenario, 5mpg, if was a combination of lower psi, windy day, air con on at lower than the usual temperature... But the drop you're seeing, is likely to be related to more often regeneration.
Also, just to be more accurate, are you using fuel from your usual petrol station?
Funny fact, for petrol, always used shell. For diesel, the golf Mk7 and the CX5 returned better mpg using shell. My partner's A Class gives better mpg using BP. My A Class, at the moment, using shell, but will try BP. But the variance, measured, not the reading from the computer, wouldn't be more than 3mpg.
Good question; yes, I am.
To be honest, the only suggestion, considering tyre pressure and other variables are at least similar to your usuals, I would check for the regenerations. Normally, simply checking every few minutes the instant mpg reading from the car should show a drop, which will last for a while, as the regen takes a bit of time to complete. Using cruise control wouldn't allow to feel the engine slightly strained, but will be easier to check the instant mpg, as the acceleration is constant, not likely when the driver is controling the acceleration.
My worst experience, was 2 successfully completed regenerations in an interval of 400 miles. Quite often, the passive ones are enough, just requiring one active time or another.
And one thing to ignore, even if your average mpg was lost, either.by reset or simply battery disconnected, the only thing that will require time to adjust is the estimated range left. Let's say you drive a 1 mile trip after the reset. Average 20mpg. The range will be based on the 20mpg. As your trips/miles driven starts to reflect your routine, the range tends to be more realistic.
More complex problems, parts related, would be flagged during the inspection performed during your last visit to the dealer. Also, as you're familiar with the car, any major issue would be noticed.
My worst experience, was 2 successfully completed regenerations in an interval of 400 miles. Quite often, the passive ones are enough, just requiring one active time or another.
And one thing to ignore, even if your average mpg was lost, either.by reset or simply battery disconnected, the only thing that will require time to adjust is the estimated range left. Let's say you drive a 1 mile trip after the reset. Average 20mpg. The range will be based on the 20mpg. As your trips/miles driven starts to reflect your routine, the range tends to be more realistic.
More complex problems, parts related, would be flagged during the inspection performed during your last visit to the dealer. Also, as you're familiar with the car, any major issue would be noticed.
Funny fact: don't use shell, it's over priced. Use Tesco 99 for petrol and Anywhere for diesel.
Caporegime
- Joined
- 21 Jun 2006
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Did they replace the air filter?
Did the screw back your air intake properly? It could be loose and the engine isn't getting as much air as it should. So not working as efficiently.
There's very few things that I'm not ready/willing to compromise: fuel, food, tyres and footwear. So far, every time they I ever considered cut few corners on those, somehow backfired.
But I understand that some people may be more adventurous.
About the fuel, isn't just about RON. And for diesel, is the lesser concentration of biodiesel. And all the lubrificante and cleaning agents present in the fuel.
Again, some people may disagree, but as I never had any fuel related problems using shell or BP, but experienced lower mpg using Sainsbury's and Tesco, the extra 2 or 3 pence per litre around my area isn't a deal breaker for me.
Associate
Are you basing your mpg readings off the trip computer or by actually measuring how much you have used and calculating your mpg yourself?
Not sure if the question was for me or the OP. Mine I always calculate. And use 99% of the time the same petrol station and more often than not the same pump.
The only real use for the trip consumption is to check if a regen is taking place. Must to be fair, mine isn't too far off. I would say about 5% tops.
Sounds like your the type of sucker Shell relies on
Shell use less ethanol in vpower afaik, so you'll get a bit more MPG from it.