From the Mitsubishi web site
"Eco mode is an energy-saving control for the engine, air conditioning and 4-wheel drive system. It suppresses engine output to ensure gentle starts, reduces the air conditioning load and automatically switches to the fuel-efficient 4-wheel drive eco mode."
Basically consider that everything will run at 80% efficiency so 0-60 in 15 seconds not 11 seconds and air conditioning more like an air cooler than an air conditioner. As for the 4 wheel drive bit, I have no idea!
Still waiting for mine however when I test drove it I found that taking off in Eco mode at lights it felt a bit sluggish in comparison to Normal mode. However my driving style in my current car tends to be more "Eco" friendly anyway so found that Eco mode in the Outlander was fine.
