The word "Eco" in EcoBoost is a total joke. Either meaning economical or eco-friendly. Turbo-charging a smaller engine can get you the same HP and or torque as a larger engine, so you think, "smaller engine, less gasoline". But, to achieve, the same power, you have to floor it. Then you get the boost, squirts in more gas, more power. The only eco savings is during idle.
There is some minor weight savings if you compare a V8 engine to a V6 with turbo. The V6 is a bit lighter. Less weight to haul, more gas savings. It's very minute though when you talk about SUVs total weight.