Gas Mileage differences between modes
Melting Slicks
Joined: Dec 2005
Posts: 2,017
Likes: 169
From: SE VA VA
IDK if the controlling code alternates which cylinders are firing...
Advanced
Joined: Sep 2014
Posts: 91
Likes: 2
From: NY NY
It apparently was set up to always cut out the same cylinders in V4 mode, which I thought odd also. The only reason I could think of why that would be done is if they have some dedicated valves to open up the cylinders to allow them to freewheel in the mode. I doubt it's simply cutting fuel and spark, as that would incur pumping losses that would negate the savings.
Racer
Joined: Jan 2007
Posts: 314
Likes: 36
From: Bolton Ontario
It apparently was set up to always cut out the same cylinders in V4 mode, which I thought odd also. The only reason I could think of why that would be done is if they have some dedicated valves to open up the cylinders to allow them to freewheel in the mode. I doubt it's simply cutting fuel and spark, as that would incur pumping losses that would negate the savings.
Even if it only gives a very small amount of fuel savings, that would be enough for GM to use it. Meeting overall corporate fuel economy goals is getting tougher all the time and anything a manufacturer can do to get there, they will.
Melting Slicks
Joined: Oct 2013
Posts: 3,006
Likes: 477
From: Las Vegas Nevada
I have a lot of elevation changes during my daily commute. I've found that I get good gas mileage in V4 mode. However, the car is constantly slowing down and jumping back into v8 mode when cruise it set. Given that, I find I have better results leaving it in SPORT mode and 7th gear instead. This is what I will do from now on.
Instructor
Joined: Feb 2014
Posts: 222
Likes: 4
From: Daytona Beach Florida
I have a lot of elevation changes during my daily commute. I've found that I get good gas mileage in V4 mode. However, the car is constantly slowing down and jumping back into v8 mode when cruise it set. Given that, I find I have better results leaving it in SPORT mode and 7th gear instead. This is what I will do from now on.
