For open freeway driving, cruising at 60 is decent. Gains could be found using DWL
, pulse & glide (neutral), pulse & EOC (given rolling hills), or drafting.
That said, on the freeway P&G or P&EOC is too much work for too little gain unless your car is dense and very aerodynamic. I EOC down one freeway hill on my commute but otherwise I do something similar to DWL (DWL doesn't apply on my carbureted car but I keep a target vacuum level in mind).