2015 GLC 250d Prem Plus Fuel Economy

[CGillies90]

Hello,

Ive just recently purchased a GLC 250d Prem Plus and the car is returning very bad MPG. Its been in and checked by Merc and they are saying the fuel economy is normal. Personally I believe im just being fed lies but just wondering if I can have some more opinions on this...

Car returning about 22mpg on short journeys and I got 31 mpg on the motorway the other night with an average speed of 40mph(3 miles urban, 10 miles motorway), 20 minute journey..

The dealer has said the car was returning 43 mpg when they road tested it... but they have went out onto the motorway and reset the computer whilst the car is at 55mph, as the averages speed they have given me is 55mph and then took that as the reading.. As soon as we come off the motorway the reading plummets. A different tech at the dealership then said that the car was returning 50/60mpg.. Just being given complete contradicting information.

Tank to tank I returned about 300 miles to a full tank of fuel.. Although this was about 75% short journeys and 25% on a run.

I am now just being palmed off and told because there's no software faults that the car is running fine.. Car had a starter battery replaced as stop/start wasn't working, however that's not affecting the fuel. Within 4 days of it being replaced it then needed to be charged again when it went back in!

Have had nothing but bother with the car from the day I got it.. Horrendous Condensation inside and bad smell, Screen washers not working, Bad Fuel economy.. Feel like this list will just keep growing but hope I can be proved otherwise and get this resolved.

Any input on any of this would be greatly appreciated.

Cheers

 

[Gazwould]

https://www.honestjohn.co.uk/realmpg/mercedes-benz/glc-class-2015

 

[CGillies90]

https://www.honestjohn.co.uk/realmpg/mercedes-benz/glc-class-2015

Hiya mate,

Ive been on that website but its very vague in terms of what style of driving.. Hoping to get someone to tell me what they are getting for driving around town for a full day vs mixed vs motorway on long journeys at say 70mph..

Those figures on the website range from 31 to 51 so even assuming that the 31 average is town its still at least 10 mpg more than we can get.. The dealer says its because were doing majority short journeys and the trip computer needs time to adjust etc.. If I were to driver about town all day our car would be at about 20mpg. absolutely brutal.

 

[Scooby_Doo]

Mine's a 250d C class and my commute to work is 11 miles and get about 33 mpg. During the summer regularly do 40 mile + trips , no dual carriageways, and get 44 mpg.

 

[DSM10000]

You have a relatively large and heavy car being powered by a 2.1l diesel engine and by your own admission your journey type was 75% short trips.

On top of this, it is Winter and with diesel, being thermodynamically more efficient they take longer to warm up in cold temperatures and use more fuel for the same journey than they would in the summer.

You must also remember that if driving in town with stop/start traffic then you are effectively covering zero mpg when stationary with the engine running.

My E320Cdi will return between 38 to 45mpg on a motorway run but I have seen it drop to 23mpg in the summer in town traffic.

 

[ioweddie]

My C Class Estate 2015 220d has averaged 40mpg since new...now 26k miles In cold weather on short runs around the IOW its about 35mpg..In warm weather mixed driving conditions from the Isle of Wight to Ascot it does 55-60 mpg frequently...
Sounds like you have a problem...Is it getting up to temperature? (Thermostat)....Are your tyre pressures correct...Have you had the Co checked (MOT)

 

[CGillies90]

It is getting up to temperature yes.. and all tyre pressures are correct. I understand its a heavy car, however I know someone else with same car and they seem to still be getting around 10 mpg more than me so really wanted to see if this was across the board.. Sorry the Co? Not following with that?

The service manager took it last night as I said and over a 100 miles basically could only get 43mpg and that was sitting at 55mph and resetting the trip computer while the car was up at speed on the motorway, which will obviously give a greater number but its not realistic driving.. Even the extra urban cycle states an average speed of around 40mph.. As soon as the accelerator is even touched it just seems to plummet the figures.

Regardless of weight and short journeys I find a 2.1 diesel doing 20mpg unrealistic without there being a fault My golf R used to do around 18mpg when I was giving it a kick in so not buying these figures They just don't seem to want to check anything as the software says the car is fine so thinking a hardware issue is bound to arise at some point and just not showing up on the ecu yet..

 

[clk208]

Get it plugged into a STAR diagnosis at an independent dealer. May well be an oxygen or nox sensor needs replacing which won’t necessarily show a fault on the dash.

 

[CGillies90]

Get it plugged into a STAR diagnosis at an independent dealer. May well be an oxygen or nox sensor needs replacing which won’t necessarily show a fault on the dash.

Surely the dealership would've seen that though? Its been plugged in already with them twice?

 

[Fununcle]

Surely the dealership would've seen that though? Its been plugged in already with them twice?

Yes but you don't believe them so I think the advice is take it somewhere else.

 

[DSM10000]

Comparing two cars in different circumstances isn't going to help. The Golf was lighter and had a different transmission etc.

Is this car new?

If so they do get better after some miles. Also, do not measure consumption by the trip meter. Only a brim to brim check is accurate.

 

[CGillies90]

Yes but you don't believe them so I think the advice is take it somewhere else.

Fair point mate

 

[CGillies90]

Comparing two cars in different circumstances isn't going to help. The Golf was lighter and had a different transmission etc.

Is this car new?

If so they do get better after some miles. Also, do not measure consumption by the trip meter. Only a brim to brim check is accurate.

Aye a know that, im just implying ive driven this thing as gentle as possible to get the most out it and its still reading that.. If I were to drive without considering fuel as much,(I don't mean hammering it) I reckon it would probably be about 16/17mpg. Its a 65 plate with 55k miles on it.

The last tank of fuel brim to brim was 300 miles.. 62 litres of fuel. 22mpg average

 

[Gazwould]

I'm perplexed at the amazing over helpfulness of some threads , people need to dial in , this particular engine , this particular car , year even !


Reminds me of two people arguing over remapping , useless Vs excellent , both gained around 40 bhp but there was a 1000 Kg vehicle weight difference , FFS....

 

[CGillies90]

I'm perplexed at the amazing over helpfulness of some threads , people need to dial in , this particular engine , this particular car , year even !


Reminds me of two people arguing over remapping , useless Vs excellent , both gained around 40 bhp but there was a 1000 Kg vehicle weight difference , FFS....

Not got a clue what you are on about with that statement

 

[geoffus]

Maybe obvious but have you service history with this car, recent air filter, etc ?

 

[Gazwould]

I don't know wether to book a haircut or hang out the washing...

 

[CGillies90]

Maybe obvious but have you service history with this car, recent air filter, etc ?

Apparently it was serviced 1k miles ago, but that's debatable as its an indy garage receipt and doesn't look the most convincing Mercedes history upto that one.. so aye that's a valid point, its probably not even been serviced in a while possibly.

 

[Daddyoftwo]

Hi see my post this evening. What temperature is it running at? When it is turned on does the top hose to the radiator get warm, ie perished seal in thermostat. Does it stay cool when when engine is hot, eg disconnected cable to thermostat / stuck closed (engine temp might not go hot as electric fan seemed to take care of it on my car).

Also try a Terra Clean

 

[Daddyoftwo]

Even if you think car is running at correct temp if thermostat cable / sensor isn't working correctly then economy will be appalling. There wasn't any OBD2 error codes with mine. Unfortunately thermostats are silly money for mercs (mine I think was £192 on eBay for a genuine one without fitting - an e350d) compared to £20 for my old Jag and 10 mins to swap over myself. But this was the cause of my terrible economy with Terracleaning making it superb (for the moment)