So something very interesting happened in my C63S coupe yesterday.

I was driving around attempting to run the 91 octane fuel in the car down as low as possible so I could then put race fuel in the car. This is what I usually do (this is the 3rd time I have done this)...that way I can switch over to my "race fuel" tune in anticipating of running a 1/2 mile event next month. Don't want any 91 octane in the tank (or very very little) when I switch over.

Anyway I got the warning on my screen to fuel soon (picture of car with a red gas tank filling the car). Have you guys ever seen that picture pop up on your screen? I have not and like I said I have done this drill before. Usually run it down to around 14 miles left (about a gallon) and had gotten the low fuel (in yellow sign) but not this new one. Anyway this new picture popped up on my screen earlier than I had anticipated because the screen had said I had 26 miles left (wish I would have taken a picture).

Problem is I am still a little distance from where I get my race fuel. So I click over to comfort mode (from Sport +) and start driving very easy. Traffic is pissing me off...LOL Anyway I am finally on the road where I get my race fuel...maybe 1-2 miles from the station and for some reason I decided to take my foot off the gas pedal and coast (just to make sure I make it)...and the screen immediately shows "GLIDE MODE"...I have never seen this before and had to do some research and according to the attached (see below) the car has to be in ECO mode to do this and it was in Comfort mode...not ECO mode. I am wondering if due to the "very low fuel" the car somehow went ahead and selected this mode to help me get to the gas station??? LOL

Any thoughts or experience with this glide mode?

 

My c63s does the same thing if its in comfort and autostart/stop is on. It doesn't matter how much fuel is in the tank. It's a feature that i barely use ,but for a nice long road trip it does work.

 

You know what...I probably had the auto start/stop on so that explains it...thanks.

Usually the only time I am in comfort mode is when I first start the car for the day and the AMG temps are "blue" and I always turn off the auto start/stop...once the oil temp goes "white" then it never leaves at least Sport mode. In my attempt to make it to the gas station I put it in comfort mode to keep the revs down and must have not disengaged the auto start/stop.

However, I think I need to come up with a different approach to converting to my "race fuel" tune. Maybe once I get to the last two notches on the fuel gauge...time to head to the gas station???

 

My car enters the "glide mode" when I am driving in comfort and take my foot off the gas pedal. It doesn't display the words "glide mode" but a little image of a sailboat shows up in the dash.

 

Brother that's funny haha I can't believe you hadn't seen it the whole time up until now. You never drive with ECO on, huh! Me neither. But it's actually pretty good for long trips and saving on gas and yep, you were definitely in ECO mode 😝

On a long trip i'll use the fancy shmancy Distronic cruise control but even if ECO mode is on, I never see it go into Gliding mode? Has anyone seen theirs do Gliding mode with Distronic ON? 🤔

PS: Here's a description from the C63 205 technical introduction book:

 

On my E63, glide mode is suppressed when cruise control is on. I'm sure it's a safety thing. If someone cuts you off, they don't want to spend extra milliseconds getting everything engaged for panic braking and/or evasive action.

 

Ah, there you go! Makes sense 👌

 

I love glide mode, it’s a great way the get some extra MPG’s on the highway when you’re on a road trip or long distance.

I’ve gotten some incredible MPG numbers using it along with gentle inputs (staying out of boost/high load). It makes my old N54 335i look like a gas guzzler in comparison.

 

I have seen the little image of the blue "Sailboat" up in the top left hand corner of my screen (while on the AMG screen) but never cared enough to find out what that was because it didn't happen too often. Now I know...thanks.

But what happened in my original post above was the words GLIDE MODE appeared in large letters in the middle of my screen (again while the screen was in AMG mode)...or at least I thought that was what I saw because it "kind of" freaked me out and I gave it some gas and it disappeared...LOL

 

Hey Brother...nope never saw it literally spell out GLIDE MODE in the center of my screen...I have seen that silly blue sailboat symbol a few times but ignored it...LOL

And I don't use comfort mode much and the only long trip I have done in my AMG was about 2 hours one way and most of it was through mountain passes and very cool curvy fast roads so not much coasting...LMAO

 

Wow I never heard of this feature. Looked it up on my FL model manual, and apparently Glide Mode can only be activated if the drive program is in I* with the drive setting to Moderate or Reduced.... I don't know if I've ever seen this icon, and my individual mode is definitely not at Moderate or Reduced drive setting... will have to experiment with this now

 

Yeah, same on my E63. I have I configured to be all the same settings a C. I can glide in I but not C. Another mysterious Stupid Mercedes Trick but the manual is clear. They're really paranoid about glide mode. But if I'm just riding around town, why not? Save a bit of gas for the next WOT freeway entrance. And the sailboat is cool.

 

So weird that it would be different setups in different models?

I do not expect to ever see it again unless it pops up when running in comfort mode while waiting for the car to warm up.

I don't care about MPG...That is what my daily (Honda Civic) is for...LOL

 

I think it kinda makes sense. AMGs don't have an E (Eco) mode, so Glide mode shouldn't just be active in Comfort mode. Those who want Glide mode can essentially setup the equivalent of an Eco mode in I*. I'm currently driving a crappy GLB loaner, and I just tried E on the way back from getting coffee. IMO, Glide mode is counterproductive around town. When I took my foot off the throttle to slow down for a traffic light etc. it entered Glide mode. The car was still slowing down, but not quite as much as when coasting. However, in Glide mode the engine keeps burning fuel, whereas when coasting, the fuel is actually cut off and the engine turns from the momentum of the car. Yes, that slows it down more, but around town that's generally why you take the foot off the throttle, so while you are coasting to slow down you are burning zero fuel, whereas while gliding, the engine still burns fuel to idle the engine. I can see Glide mode to help when driving on the highway as you can glide under the car's momentum while reducing the amount of fuel burned and not have the car slow down too much from the engine drag. On cars like the Audi e-tron for example, Glide mode is tied to GPS, so it decides between gliding or regen depending on what's up ahead. If it sees that you are approaching traffic, traffic light etc it uses regen to slow the car down, but if there's nothing ahead it glides instead, but as opposed to an internal combustion engine, the electric motors actually use zero electricity when gliding, so you truly save energy.

 

When gliding the engine is idling, so it's using less gas than when engine braking. Fuel is absolutely being delivered on the overrun, and more than when the engine is disengaged and idling. So I don't see what the downside is. Therefore, I wouldn't mind if C allowed glide mode so I could use I* for some performance settings.

 

That's not correct. There's no fuel delivered on the overrun in C. Yes, in S+ it is to create the pops. Fuel is completely cut off and the alternator voltage is increased to recuperate some of the kinetic energy. If the consumption goes into the green Charge part of the graph, then there is zero fuel being burned.

 

There's obviously an RPM minimum for overrun fuel cutoff. It would be nice to know what the M177 engine's is set to, in other words, how much this is practically effective.

But the other difference between OFC and glide mode that you haven't mentioned is frictional loss. When I'm in glide mode on a fairly level (or very slightly descending grade), it stays in glide mode for quite a while. There's a section of road between my house and the post office where I lift my foot sharply at 40 mph and glide for about 1/2 mile. I have dropped to about 35 and usually slow at that point for a light. If I were not in glide mode but merely coasting with throttle closed, the car would slow very rapidly. "Engine braking," even with no fuel delivery, is largely the result of drivetrain frictional losses. By disconnecting the drivetrain, the car is able to maintain speed much, much farther. I would never come close to this distance traveled, effectively in neutral, with the transmission engaged. If there is a more significant, but still gentle, downgrade the difference will be even more dramatic.

 

Yes, of course if the rpm drops too low, then the transmission has to disengage and the engine starts burning fuel again. That happens at a fairly low rpm close to idle. At that point it's no different from glide mode, but up until that point it doesn't burn fuel.

Yes, glide mode makes sense if you are actually gliding for a significant distance. That's kinda why it makes sense to tie it to GPS. In your example it would know that you have 1/2 mile to go before the light, so it can take advantage of gliding. That's not a typical scenario for me, though. It's generally flat around here and I start slowing down much closer to the light. In glide mode, the GLB I'm driving now actually quite rapidly lost speed on flat ground. It's obviously not the most aerodynamic thing, so probably not the best example, but it started rapidly dropping speed from 35 down and I hate being somebody who creeps up to a light like a grandma.

In all honesty these are drops in a bucket on the C63. I bet any fuel savings you get from glide mode doesn't even register in the grand scheme. This is the wrong car if you are looking to drive economically. I get impressive mpg on longer highway drives, but around town it does in the 12s. Glide mode or Eco Start/Stop won't make a noticeable difference. It's all just to game the test cycles so they can show a higher mpg on the window sticker.

 

Glide mode works wonders on the highways here that have lots of elevation changes. There are some very long stretches of highway with declines that definitely help with overall trip MPG when highway driving and being very conservative with throttle.

I think the best I’ve gotten out of this car is around 27 MPG (US) tuned which to me is pretty impressive considering I had a Cobb tuned BMW 335i (N54) that I was lucky to get 18-20 MPG on the highway trying my best to conserve.

Honestly though, it’s impossible not to slam the throttle with this car - screw average MPGs, let them drop!

 

Glide mode or not, this car is all about smiles per gallon. Not miles per gallon.

 

I did some testing on a FL model and did get glide mode to work, although not consistently. I guess it makes sense that I would have to be going above a certain mph (I think it looks to be ~30 mph) but "glide mode" wouldn't activate sometimes after I got on the throttle hard a bit.

In the end, I didn't notice an MPG gain or loss when using my individual mode set to comfort so I could "glide" haha. I was curious about the tech but I'd rather just let distronic drive for me while battling stop and go traffic on the free way. Glide mode won't activate with distronic on so... fun experiment, but not for me.