Hi,
Since this is a tire replacement post, I'd add in my latest tire purchase.
We own 2 2011 Leafs which we replaced all our tires recently. We chose Bridgestone Turanza Serenity Plus 205/55/16 91H which have a 80K mile warranty. These tires has a tread rating of I recall 800 which is double of the Ecopias.
The Serenity Plus (this is also a Eco-rated product from Bridgestone) is a slightly heavier tire, but it clearly looks and feels much stronger than the Ecopia. The sidewalls were definitely thicker, and amazingly with a super quiet ride. I like the handling of the tire, although I cannot say much about the % loss of range. Regardless, I am happy with these tires.
The price was $123 a piece but we got $70.00 off all 4 for a price-match deal. And, on top of that, Bridgestone also had a $70 prepaid visa promo which we claimed by submitting our invoice.
Another forum participant "braineo" (search his posting) had also bought similar tires and reports a 5% loss in range, but I think it may still be too early/new to rate it.
We hated the Ecopias, although we got 28K miles out of them, the wear was very uneven on BOTH vehicles. They were absolute junk tires. All the time, it felt like we were riding on thin rubber.