I don't think the "eco" concern with topping off is weight related. I think its with overflow (spillage) and that's definitely something I've noticed with the Raptor. For whatever reason, when the pump clicks off, it really means full. When I try and top off beyond that, a few seconds later I'll notice gas spilling out under the cap and onto the pavement. Money out the door (oh yeah, and of course I'm ruining the planet too
icard
PS: I paid $3.50 for E85 yesterday. The same station had regular unleaded for $4.40. Although that's WAY too much for E85, relatively speaking I was happy to pay it.