Assuming the gas prices will steadily rise, it could actually make more financial sense to try to squeeze as much mileage out of the X now while prices are circa $3.

I had considered parking the X and driving my Altima for a while. I could do this for the next few years and rack the mileage up on the Altima. Assume the gas price closes in on $5 around this time and I'll have a low mileage SUV that will cost too much to run and be even harder to sell and a high mileage car that is closer to the end of its life cycle.

Better for me to drive the X now because in 10 years we'll look back to the good old days when gas was only $3/gal.