jaws3

This is a very valid point for Canada. I bought a 2021 2500HD Duramax High Country last week and returned it to the dealer this week. Consumption was such that on the standard tank I would hardly get 500km. I do regular trips of 650km starting after work on Friday at 5pm and going to Northern Manitoba. By the time I reach the remote areas, all local gas stations are closed. I could take a detour (adding 45 minutes to my trip) to fill up at a rural town along the way (that has 24/7 fuel), but that does not suite me. I've been doing this trip for 3.5 years with my 2017 2500HD Duramax and had nearly half a tank left by the time I reached my destination - every time. Having the same engine, I was shocked at the poor consumption of the 2021 L5P. It has been back at the dealer for 3 days but as yet there is no word on why the consumption is 4 times that of my 2017 L5P. I did look into fitting a larger fuel tank but blowing another 2 - 3k on a brand spanking new truck just to allow me to take a long trip, is not worth it. Guess I'll be taking back my 2017 truck and leaving the dealer to sell the 2021 guzzler to someone else. But your comment is very valid for Canadian drivers. And that is what I explained to the dealer when I returned the truck - it is not usable because it does not fulfill me needs.

No regen message, no regen smell that I am used to with 2017 Duramax, no high idle that I used to have during regen on 2017. I don't think it is in regen mode but appreciate your input.

It's going back to dealer on Tuesday as soon as they open after long weekend. After my earlier reply, I went out and did another 100km trip but consumption is atrocious. Something is wrong .

The consumption shown on the pic is from my 2017 LP5 that was traded. The HC LP5 I'm driving now only gives me 28 - 32l/100km on highway. And this was on a "special" highway run to see what I could get with just me and the wife, no cargo and feather-footing the pedal. I became so frustrated I abandoned the exercise after a while and just went home and parked it. In town consumtion is anything from 34l/100km to "off the charts". Not impressed but this is another topic not related to your original question - my answer which I hope shed some light on your question. And on that topic, I do find the 2021 taking longer to warm up the heater to make the cab comfortable. On a trip less than 13 minutes it barely heats up the cabin (again this is during the cold spell of -50C). That being said, the 2017 was faster at heating the cab in cold weather.

Hi, have only had my 2021Duramax HC for couple of days but with the current cold spell of -50C in Manitoba I have had no issues with cold start. Forgot to plug it in 3 nights ago but it started next day without any issue (sleeps in unheated garage). I am very concerned about fuel consumption though. My 2017 Duramax LTZ was amazing at anything form 6.9l/100km (wife driving) to 8.7l/100km (my own heavier foot!) on highway trips. Around town it was an average of 11-14l/100km depending on how much warm-up idling I did. I am considering returning the 2021 to the dealer and taking back my 2017. As you can see on attached pic of 22 Jan 2021, these were real life numbers on my 2017 while using the "50km distance average" setting .. The new features in the HC are not worth sacrificing a perfectly good 2017 with only 54k on the clock and zero problems.

Have an appointment with the dealer next week to look at this again

Thank you white94. In my original post I stated this has been going on for 2 weeks since the software update. It includes daily driving as well as a 1200km weekend trip. Surely that should be far enough? I have also noticed over the past 3 days TV that the gear change occuring just above 50km/h is very rough. As if the truck "jumps" at that changeover. Not sure if it is related but the truck is rapidly becoming very unpleasant to drive. Will make another call to dealer as that seems to be my only ootion. Apart from selling it.

Yes, idle never returns to baseline. This is not a "variable" idle rpm. It is over 800rpm all the time. Except at start up when it will idle at nase rpm ut as soon as I drive off and stop the first time, it is above 800rpm and does not ho down until I shut down the engine

No aftermarket floormats. Everything as it was prior to the recall except the 800rpm. But thanks for corroborating that it is not normal.

Good idea but not easy. Next dealer is 200km away from here...

After the recent recall for Emission System upgrade to comply with gov standards (done 2 weeks ago) the base idle speed has increased to over 800rpm. Used to be just above 500rpm. Dealer says the higher base idle speed is "with limits". I don't agree. Talked to 2 drivers of similar trucks today and both said there base idle speed is just above 500rpm. These are company trucks so they don't know if recall upgrade was performed on the trucks they are driving. The exact scenario is that when I start the engine, idle is normal at just over 500rpm. It stays normal when shifting into DRIVE. Then start driving and at the very first stop 700m from my house, it base idle is over 800rpm. It stays like that until I shut down the engine and it is back to 500rpm when I start the engine again after work. But only until the first stop when it stays above 800rpm. This has been going on for the past 2 weeks (during which I also did a 1200km highway trip). I cannot find a reference to base idle speed on this engine. Is 800rpm considered normal? If it is my "new normal" I'll be selling the truck as it is driving my crazy with the added noise sounding like a jet engine at startup.