The last time it was lowered it didn't save gas - it did a few more lives, but not gas.
AND... Cars since the 90's have been geared for 65, so 55 would actually be using more gas. It's TRUE!
If you have a trip computer on your car that gives you an instant reaading of MPG find highway with a good lengh of it being level and drive 55 looking at what MPG you're getting and then do the same at 65. I'm sure 65 will yield a better MPG.
Our Crossfires don't have one, I put a SCAN GAUGE one on my PT that plugs into the OBD II port connector and I get 22-24 MPG at 55 MPH but at 65 MPH I get 25-27 MPG.
The SCAN GUAGE is supposed to work on just about any car - doesn't work on the crossfire.