I came across a journal article a few days ago that listed findings of different researchers on the elasticity of vehicle miles traveled relative to gasoline prices.  I'm out of town this weekend, but maybe I'll post it in an open thread or another appropriate location next week.  Folks speculate on this over here all the time, but there is research out there that can inform the discussion.  

Speaking of speculation, I suspect that the key -- as you imply -- is whether the prices are perceived as temporary or permanent.  If they're temporary, then the "employee discount" on that F-250 or Expedition may not sound that bad.  

I've been looking for this type of information. I've seen some articles, but nothing that compelling. I believe you are right about the perception of temporary vs. permanent price increases.
I've been looking as some such papers today. What I haven't found yet is anything that distinguishes between the effect of prices on discretionary trips, and non-discretionary trips (ie when are miles traveled dropping because economic activity is being reduced for the drivers, and when are they just saving miles without otherwise affecting their economic behavior).