Machine13

I get worse gas mileage in Eco mode than Normal or Sport. I get better MPG’s in Normal. And I get even better MPG’s in Sport.

I do drive appx 80% city miles and 20% highway miles. I do not drive with a heavy foot. I am aware that if I did drive more highway miles then Eco mode may get better MPG’s than Sport mode. That seems obvious because Sport mode often stays in a lower gear even at highway speeds.

But in my mostly city driving, with appx two short highway jaunts per day of less than 5 minutes each, I think the reason has to do with how much less time I spend accelerating using Sport mode, both in the city and on the highway.

In Sport mode I can get up to a cruising speed much quicker, be it 40 MPH (city) or 65 MPH (hwy) and then can lay off the pedal and just cruise, saving on MPG’s sooner than Eco mode.

In Eco mode, it takes much longer to accelerate. Therefore, it uses more gas to get up to speed. I think.

Anyone else notice Eco mode ultimately using more gas than Normal or Sport modes?

Is Eco mode more of a marketing gimmick than an actual way to improve the economy of the car?

Thanks for your $0.02.

Machine13

Sorry if the fonts came out all different sizes on your device I'm not sure how that happened.

JDR76

When I had my IS350, I found no benefit to Eco mode. I would get the same mileage in Eco and Normal, but worse in Sport.

On my GS350, I get substantially better mileage in Eco than I do in Normal, with Sport or Sport + being the worst.

E46CT

Eco is not a marketing gimmick but it's more effective for turbo models than non-turbo because ECO holds boost back.

Eco has a much more conservative shift programming so your RPMs are lower. It will use less fuel all other things being equal.

You can train yourself in power mode to save fuel though. Still possible to get good mileage.

Raghza

The Eco mode turns down the AC and reduces throttle response. So if you're in heavy traffic, constant accelerating and braking would give you better mileage.
In steady cruising I don't think the Eco mode makes a big difference.
And I've also noticed the same thing about heavy acceleration and Eco mode - you need more throttle and more time to get up to speed, so it will lower the mileage.

I just use Eco mode when going through heavy traffic and during rush hours.

arentz07

+1, for V-6 models anyway, the biggest differences with Eco mode are the throttle mapping and the HVAC operation. For example when it's cold out and the engine is cold, if you leave the mode in Normal or Sport, the car will idle up around 900-1000 RPM when at a light. If you turn on Eco mode, the idle drops down to the usual level (around 600 or so). So I guess you'd get better gas mileage overall in city driving, in theory. And of course, the Eco throttle mapping is no fun at all.

MX73

Eco mode doesn't drop the idle and my IS never idles at 900-1000 RPM in Normal or Sport. Yea, it'll idle at 900-1000 on a cold start up but never after warmed up.

Eco mode will have the transmission shift to the 8th gear sooner and put the hvac system on eco mode. So yes, you will be using more fuel to gain speed but at cruising speed, you'll be in a higher gear, lower rpm and should be saving a bit of fuel.

arentz07

That's what I said - when the engine's still cold. It's pretty consistently doing that for me if it's below freezing outside and I have the heat running, unless I am in Eco mode. Stops doing that after 5 minutes of driving or so.

MX73

What I'm saying is the drive mode doesn't affect idle speed. Eco, normal sport\sport+ doesn't affect idle speed. It'll say at 800-1500RPM on cold start or 600-700rpm after warm up in any mode. RPM will increase or decrease based on the load like the HVAC or operating an accessory.

arentz07

I'll post a video later...

Edit: Oh you just edited your post. Yeah the idle is related to HVAC load, which is affected by drive mode. So in essence, yes, drive mode can affect what the engine idles at, but it's by way of the HVAC load.

MX73

I leave my car in eco mode all the time. I can go out to my car and observe cold start up idle which right now will idle at 1500RPM in any mode and 600-800RPM after 15 mins of warm up at idle.

arentz07

OK, but does it spin at a higher RPM at a stop sign or traffic signal, after you've started driving? Sitting in the driveway is one thing, but sitting in traffic is what I am referring to.

Question: If I am stopped, in Drive, and the engine is still spinning, isn't that also called "idle"? Not sure if that's why this is confusing, but I may be using the wrong word.

MX73

In drive, there is a load on the engine while idling at a light. The drive mode select doesn't affect idle there either.

It doesn't spin higher at a stop. The computer adjust idle to prevent the engine from dying.

arentz07

Fine, I'll post a video demonstrating what I am talking about later. For me, it's very noticeable. Been that way since the first time I drove it in cold weather - so it seems very intentional. I might also add that I leave my HVAC controls on Auto most of the time, so that could also be a factor - if you're manually controlling the heat this may not happen to you.

MX73

That the key there. HVAC. It signals the computer to compensate for the additional load. Not eco, normal or sport. The only thing Eco, normal, sport or sport + does is adjust the throttle response, remap the transmission shift pattern, adjust the HVAC system, or on the Sport + adjust the suspension and steering firmness. It's like this on all the newer Lexus that I have driven in.