jcoe

Going up hills, I noted the eco lite remained lit during the downshift mandated by cruise control to maintain preset speed. However, during ascent with cruise control off, and slight decrease speed (no downshift) the eco light will go off. Kinda counterintuitive, that slowing down during ascent would be less economical than maintaining set speed during climb. Any explanations?

Marqevans

I checked the menu buttons on the steering column an it says Eco is off. Could not get it to turn on through the column no matter what button I push.

studies01

Methinx the ECO light indicator is only a modern rehash of the old vacuum gages one could buy. These units [the vacuum gage] were a function of intake manifold pressure/vacuum and operated very loosely as gas mileage indicators to the unsuspecting driver. The more you stepped into the throttle, the lower manifold vacuum dropped and it assumed, the lower your fuel economy dropped too!

When coasting or driving down hill with minimal-to-closed throttle, manifold vacuum would "sky rocket" to high numbers and it assumed, so would your mileage.

The vacuum gage was a better indicator of fuel mileage with older carbureted vehicles. With the advent of fuel-injected variable valve timing engines as we have in modern vehicles from Lexus & Toyota, an ECU [engine computer] "thinks" about the application of your right foot on the gas pedal whether by cruise control or your leg, checks engine loading [with vacuum & other digital sensors], fuel flow, spark timing & other variables, then decides whether the vehicle is operating [or not] in the ECO mode.

The ECO light makes it easier for drivers to see how well they are achieving [or not] the EPA estimated fuel economy rating which we all know is a proven fact.......

jcoe

Thanks Studies01. I guess we will never know. It is just bizarre because the driver is so familiar with eco lite turning off when depressing the accelerator during acceleration, yet it stays on after downshift during hill climb.