I think the marketing as an "and" car and the low first cost will insulate the Elio from the demand being so closely tied to gas prices. Right now my only vehicle is a full sized pickup because I could only afford one vehicle and needed towing capacity. The desire to have a daily driver/road warrior vehicle is about keeping miles off my truck and ease of parking in crowded parking lots, and a $20 or $30 swing at the pumps doesn't really change that. At under $10K, I can justify owning a second vehicle. The fact that gas prices are cheaper only means that I'll have more money available in my transportation budget each month. And all those folks that did pick their vehicle size based on gas prices can rush out to get an Elio when the gas prices go back up.
The real question is whether the driving experience will live up to our expectations. If I get the same grin I get from using all the power of my V8, I'll spend plenty of time in the Elio. If it feels like an economy car and can't keep up with interstate driving, I won't.
driving fast in a slow car can be as fun as driving fast in a fast car.