Sudden drop in MPG

[LowerCarcass]

Hi everyone. First time posting as I’ve recently bought a 2020 CLA 220d. I’ve noticed a few times that when I’m driving the MPG will just suddenly tank. It’ll drop from 60-65 on the motorway to about 30. I’ve also noticed that during these times, the fuel consumption meter won’t read ‘charging’ when I’m coasting or braking. It’ll go on for about an hour and then seems to recover to normal. Has anyone experienced this or does anyone have any insights into what this would be? It’s still under warranty so if it’s a fault I’d like to get it back in asap. Cheers

 

[Blobcat]

Hello and welcome

Sounds like the DPF is doing a regen

 

[LowerCarcass]

Thanks for the reply. Is that normal then?

I did a little bit of reading up on dpf regen and it says that after a long period of motorway driving it should regenerate passively as the exhaust is hot enough. Every time this has happened it’s been after about an hour of motorway cruising

 

[Blobcat]

Thanks for the reply. Is that normal then?

It is with modern diesels… how and when they regen is dependent upon many factors and if they don’t complete they go again once temp and other parameters are met.

 

[Ron240]

I’ve recently bought a 2020 CLA 220d.

Very nice choice of car...all apart from the fuel system of course.
What colour and trim spec have you got?

 

[LowerCarcass]

Very nice choice of car...all apart from the fuel system of course.
What colour and trim spec have you got?

Thank you very much. I got it in black in the AMG line plus edition. Got some nice toys, especially compared to my last car (BMW)

 

[LowerCarcass]

It is with modern diesels… how and when they regen is dependent upon many factors and if they don’t complete they go again once temp and other parameters are met.

I shan’t worry about it then . Cheers for coming back to me

 

[Blobcat]

I shan’t worry about it then . Cheers for coming back to me

If it’s doing it what appears to be an excessive amount, then worth getting codes read to see how the DPF is Filling up.

 

[Ron240]

I got it in black in the AMG line plus edition. Got some nice toys, especially compared to my last car (BMW)

Yep, the Premium Plus cabin is a very nice place to sit.