I haven't noticed any difference in behavior between eco mode on or off, so I believe it's just a light triggered by a switch that works off of either manifold pressure or the throttle position sensor.

 

It's just a light that comes on to pat you on the back for driving conservatively

 

Yes, from reading the manual, it's just an idiot light. My sales-guys (2 different dealerships) tried to tell me that it had some effect on throttle when enabled, during my test drives, but that is clearly not the case.

No big deal. Nice that you can turn it off if you want.

 

The Eco "On" or "Off" selection is only to toggle the Eco light on the dash display...it doesn't control any shift logic or anything related to the drivetrain. It is just an option if you don't (or do) want to see the Eco light coming on and off while you drive.

Edit: Posted at the same time as dguthmann...so what he said!

 

The ECO indicator is one of the worst things I've ever seen as a main component of a dashboard. How about outside temp instead? My only guess is there is some regulation that gives a little tax credit or other incentive if there is a nanny light somewhere. At least you can turn it off. (Instead of the upshift light.. Remember those? ugh!)

I don't know where salesmen are getting the 'ECO MODE' idea. Misinformed by Kia maybe? There are no modes. One of my salesmen said when it's on, it effects the AC. I told him that's ridiculous and that the compressor probably cuts back when the engine is under load... Toyota's do that. I try to help salesmen... I feel for them.. they know nothing about cars generally... and just want to pay their bills.

 

On the original 2011 Sonata the Eco light performed as it does on the 2012 Sorento. The 2011.5 Sonata and I'm guessing the Optima as well have what Hyundai calls "Active Eco" which does affect shifting and throttle response when engaged.

The salesmen who are confused may be unaware of the above distinction.

 

Personally I like the Eco light. Today I was getting amazing gas mileage using it...I stayed at 75 as much as possible and from lake Elsinore to la mirada I was getting 31mpg! On my way back (@ night) I was getting 29mpg!

 

I think it's a fair statement and reasonable assumption the indicator has some link to active programming logic to save fuel, for example, on the new Hyundai Accent GDI there is an ECO button which is supposed to give you an additional 7% gas conservation. However, I have to agree with other posters here that in this application it does not save gas, simply a reminder to ease off the throttle. A nice little marketing trick to leverage everyone's common knowledge of something similar to make the product appear better then it is. Still, you'd be hard pressed to beat the fuel economy of the GDI Sorento so perhaps the preconceived notion is appropriate despite the fact the indicator adds no additional value.

 

Still, you'd be hard pressed to beat the fuel economy of the GDI Sorento so perhaps the preconceived notion is appropriate despite the fact the indicator adds no additional value.

Wish I had an indicator on the CRDi.
The spot is there on the dash and everything... Which confuses me, as its in the tacho cluster, which would be incompatible with the petrol models anyway... Perhaps they offer it in some markets other than Australia. -sadface-

56 US MPG, though, so not bad without that light... Although one is always very tempted to floor it to hear that beautiful turbo... And surge of power.

 

As mentioned it's just a marketing thing. I remember seeing cars with these types of lights and gauges way back when. They are generally hooked up to read manifold vacuum. The less load you are putting on the engine the higher the vacuum. As you accelerate the vacuum decreases.

 

Oh, yes, now that you mention it, when I was growing up my mom's Chevy Caprice had an analog gauge for "economy" laughable on a four barrel 305 V8...

 

emissions emissions emissions. that's why we don't embrace diesel. it's expensive to put those controls on. the germans have the market on bluetec technology

 

I liken the ECO light on my 2011 Sorento to the old vacuum guages back in the day and the Turbo meter on my wife's 2007 Acura RDX. If you keep the meter close to 0 you can improve your Avg. MPG by 25%. My "fast & furious" wife unfornutely usually has her foot stuck deeply into the turbo! Bottom line it makes the driver consious of how he or she is driving and it is effective in maximizing gas mileage even though it is just a light.

 

Getting back to better shifting and engine performance. I think, though may be incorrect, that the transmission computer has a learning pattern or bracket that it operates within. V8 Fords & Lincoln Mark 8s were noted for that. You tromp on it a bunch of times before going to the track and the transmission responds with tighter shifts at maximum RPM. I've done it with my Sorento V6 AWD and have gotten better corrected performance times than what the usual motor articles state. Also worked better after 5K mile break in. Trans shifts tightly @ 6500rpm without holding it in gear. If I drive lightly with the eco light as a guide, less immediate on demand performance/rpms/shifts but slightly better fuel mileage.