Getting a hot rear end

[FarmerJim]

2015 S212 E350 Bluetec, AMG Night Edition, with 9G box. About 68,000 miles clocked up.

An odd thing which happens occasionally. After a drive, I get out and find the the back of the car is very hot. The rear screen is almost too hot to touch and the whole rear end of the car smells hot. No warning lights and no other apparent problems. It has done this occasionally for a number of years. Never really bothered me that much, but would be interesting to hear if this is a common 'feature' and/or what might be causing it.

[LunarOne]

Problem with your catalyst? Have you lost a heat shield between any part of the exhaust system and the rest of the car? Are you driving in Death Valley? We need to know more.

[FarmerJim]

Living in rural UK Cotswolds. Not aware of any catalyst or heat shield problems. Never been raised at any main dealer or indy specialist inspections.

[LunarOne]

I wonder if it could be binding rear brakes? That's a likely explanation for a "hot smell" although i can't see how that might affect your rear screen!

[Tony1963]

Excessive heat in the area of the fuel tank would worry me.

[FarmerJim]

The brakes have been replaced, with the problem occurring before and after.

I should add that it is more of a general hot smell and not a burning smell or hot brake linings smell.

[Scrump]

I have a 2014 version of the same car but with the 7g+ gearbox.
Never experienced anything like you describe. All I can think of is DPF regen.

[LordLoveLength]

Yep - almost certainly a DPF regeneration - on mercs they switch on the heated rear window to increase the engine load during regeneration but there is no indication of this in the car.
Extra fuel is injected on the exhaust stroke to burn off the soot in the DPF which increases the exhaust temperature significantly. You probably got home just as the regeneration was underway.

[FarmerJim]

Thanks all. Yes, from that it does sound like a DPF regen thing.