Here's the dealio.
I have driven a base 2007 Corolla and a 2005 Grand Prix with all of the bells and whistles (leather, supercharger, moonroof, etc.) throughout my many years of long commutes to work.
The findings will not shock you.
The Corolla was good on gas (30 mpg) but was a HORRIBLE ride - the spoiler would whistle on windy days, the steering wheel was too close, seats were uncomfortable, etc.
The Grand Prix was a BLAST to drive (and comfortable) but yielded only 22mpg. That's a sizable difference when you drive 130 miles a day and compare that number to a Prius (conservative highway mpg = 45 = 2X more efficient that the GP).
Now when you factor in $4 or even $5 (doomsayers) gas, that's a huge chunk of change (y'all have calculators).
With that said, I'm this close to pulling the trigger on an '05 Prius that is being sold at an incredibly low price considering where this market is going (think back to the summer of 08). Yes, it has high miles (still less than 100K) but what do you think I'm going to do with it?
I've driven GM cars well north of 300K miles so I have full confidence in a car that CR continually ranked the best in terms of reliability and consumer satisfaction (pre-runaway Prius models).
Yes, I know the ride will be a small step above a Corolla and the performance ('get up and go' sense of the word) will be worse, but at this point, I'm willing to trade that for an efficient means to get back and forth to work without having to get a second mortgage.