At those speeds (65-70 at long distances), you need something light, MT, and aerodynamic (or hybrid).
Most modern, non-Diesel machines won't get you what you're looking for in the speed department, other than those with a low cD and friction (e.g. Hybrid).
Rumor has it that an Orthopedic Surgeon helped design the seats in the Prius-I (I can agree that someone knew what they were doing becuase they're really comfortable and supportive).
The clear winner for highway miles is the Insight, but for long-commutes, you may regret that decision as it beats the crap out of you. After crunching the numbers from the EPA on 2006 and 2007 MY cars vs. my own database of FE and reliability, for 45 MPG it looks like:
- Prius I and II
- Civic Hybrid I (manual)
- Civic Hybrid I Automatic and HCH-II
- Yaris 3-door Manual
- Toyota Corolla Manual (almost any year, really)
- Civic Automatic (06-07)
Honestly, Diesels are the way to go for highway miles -- but it's your call as to their reliability. Remember, there are many cars not on the list above that you can squeeze 45 mpg out of.
BTW, slow down! I know you have a long commute, but you could probably get a bigger, more comfortable car if you stay around 60 and/or drive with load -- meaning:
You're moving along at 60 mph with 20% throttle on level ground. You approach a descent: stay on the throttle at 20%. Now momentum gets you going up to 70, for example, down the hill. On the ascent up the next hill, keep that throttle right where it is and scrub-off some speed. You may go down into the 50's as far as speed goes, but your average speed will still be around 60, and you've saved a LOT of fuel. That technique has yielded me MUCH better highway FE. I've modified my cruise control to do just that, and it takes away the need to focus so much on the pedal pressure.
RH77