carllangford

Has anyone ever ran a decent ECO comparison (System On and System Off)? Being an engineer and the car being a daily driver I was contemplating logging some data to/from work with the system On and Off. My commute is 20 miles and the day-to-day traffic is fairly consistent with a good bit of highway/cruise driving. The part of this I don't look forward to is ECO On where my exhaust gets quiet .

aj98

auto or manual?

On my M7, Eco wont kick in unless I'm in 4th gear or higher. 4th gear @ 70 may bring you above the magic 1700rpm for exhaust note, but the significantly higher RPM
(as opposed to 70 in 7th gear) may offset the Eco gains : )

vettman96

I have run eco exclusively through 2 tanks of fuel, then 2 tanks in tour
and have not seen any significant change in either mileage or
performance. Pulled the NPP fuse to maintain exhaust note.

Curahee

I have never used, and will never use the AFM. It's good, at most, for an extra one or two MPG at highway speeds and the "clunking" back and forth between 8 cyl.and 4 cyl. is hard on the motor. IMO

meyerweb

Manual or auto? With an auto, the car frequently goes into 4 cyl operation no matter what mode you're in (unless you're in paddle shift mode). So you probably won't notice much difference.

On a manual, the car won't go into 4 cyl operation unless you're in Eco. So on the highway, the difference can be noticeable. In non-highway operation, the MT7 car doesn't stay in 4 cyl mode enough to make a big difference.

There have been a number of posts from people who have done such a comparison. With an M7, I've seen numbers (reported on the forum) of a couple of MPG to as much as 5 MPG on the highway.

As has been posted many times, the NPP fuse has no effect on the AFM operation, including the AFM valves, which are completely separate from the NPP valves. Even with the fuse pulled, when the car goes into 4 cyl mode the AFM valves close partway to prevent the car sounding like a Honda Civic with a fart can exhaust.

In the image below, the green arrow points to an NPP valve behind the muffler. The red arrow to an AFM valve, in front of the muffler.

iclick

I've done some tests with the A8 observing on the instant MPG display, which also shows V4/V8 mode, and shifting from Drive to Manual. When it Drive it will cruise in V4 mode and in Manual it stays in V8, so when you shift it maintains the same gear selection, cruise control remains enabled, and a comparison can be made.

EPA tests show a difference of 5.5-7.5%, and with my car using only direct observation the mileage difference is in that range or slightly higher (~3mpg) when maintaining a steady state in 8th gear--e.g., highway with cruise engaged. When combining highway and city driving the difference will be less, of course, since it will shift to V8 some of the time. For me, this is significant enough to use it and since AFM is very unintrusive in my car I rarely detect it changing from one mode to the other. I don't understand the rationale of trying to reduce gas mileage when the technology is in place to increase it. I haven't seen any evidence that AFM reduces engine life or has any other adverse side effects, apart from occasional sensations when shifting from one mode to the other, and GM's second-generation AFM technology has been tested since 2004. AFAIK it has been reliable.

jedblanks

2015 Sierra has AFM. Makes 0% difference. I get 15 City, 16 mixed and 20 all Hwy.

I get 22mpg in mixed driving with the C7. That's good enough for me. M7 never goes into Eco unless I set drive mode to ECO. Nah!

The only use I could see is if I had the cruise set on 70 in 7th for 300 miles. Then I might switch to ECO drive mode, but I've never been in that situation. Even then it might get 30 instead of 29? Probably not worth it.

I suspect GM only has these modes on current models as a Beta test for more drastic things to come to meet EPA mpg goals.

BenCasey

I've been keeping stats... I would say that using ECO mode and doing the 1st to 4th shift in traffic significantly enhances fuel economy. It also deadens your spirit and makes it harder to go fast when you are depressed. I call this the double mastectomy hot wife problem.

When in SPORT mode, my mileage plummets. I drive much more like a total arsehole, get high off the exhaust note, and will drive down a 45mph road entirely in 2nd gear. This is the new wife is only 26 syndrome. Suddenly erectile dysfunction no more.

I cut it down the middle. Drive to work in ECO depressed and impotent, drive home like a **** star.

10 mile commute, lots of short trips, I get almost 19 with 1-4 shift and eco. In sport mode, I can get as much as 15mpg. This is per tank. Some of my trips I only average 7mpg.

On a 1200 mile drive at 85mph, I average 25 in eco and 21 in touring, I love Eco on the freeway. Nice and quiet, saves gas that is not relegated to combating erectile dysfunction

carllangford

Funny

I'm just going to collect some data To/From work by resetting Trip Meter B before each trip and recording the end result. 20 mile commute with 14 miles of unimpeded freeway in the morning and about 8 unimpeded freeway miles in the evening. The morning trip is more predictable. I'll make the drive in the M7 with and without ECO enabled. I'd like to know what to expect when I make a 300+ mile drive down to the Gulf.

davekp78

I did a test a few months ago. About 60 miles each way on I-95 in flat Florida. At about 75mph I got 2 more mpg in 4 cyl mode with my A8.

Internetguru

My car has an eco mode? I cringe every time I spin the dial the wrong way and round the horn to sport mode ASAP.

I had Jr. pull my fuse so my exhaust is set to always loud... Now she purrrrs no matter what. And my lead foot never seems to allow it to go into eco mode. Getting 11.8 mpg and loving it.

defaria

You do know that your second statement totally negates your first statement. I mean if you have never used AFM then you would not know that it's good for only an extra one or two MPG. BTW it's good for a lot more had you ever actually taken the time to try it.

carllangford

Here's a start to data collection with ECO turned off, where the data is looking fairly consistent. A week of this followed by a week of ECO enabled should do though I'm 1/2 tempted to turn it on tomorrow and Friday.