Premium Grade Gap
Motorists stuck with vehicles taking premium gasoline have more reason to gripe: in follow up to analysis done last year by GasBuddy, the "grade gap", or price difference for premium gasoline versus regular, continues to rise. (Click here for larger graph)
Last time we wrote about the "grade gap" rising, the cost for premium nationally averaged about 35 cents higher than regular. Today, as the updated chart shows, we're closing in on a grade gap that's approaching 40 cents per gallon. Some media outlets are even covering the grade gap in news stories, calling the rising grade gap a "hidden increase".
Indeed, it seems far fewer stations are posting the price of premium outside their station- I've certainly noticed it common as I drive back to my home state of Michigan from my residence in Chicago, IL. 
Most of the reason for the rising grade gap are the same as they were last time we wrote about it: declining sales of premium, less production of the higher octane fuel has led to higher prices.
It seems impossible now to find stations with a grade gap of 20-cents per gallon (meaning premium is just 20-cents more than regular), but it is possible, and using GasBuddy, even the stations that stayed at the 20-cent gap in Michigan City, Indiana have largely disappeared. One "rogue" station (I won't name it so it doesn't raise its premium price) in Hammond, Indiana, still maintains that seemingly meager 20-cent gap, and it's my new favorite station when I'm making the drive to Michigan and back.
For all those that can't find a station at the all-but-gone 20-cent gap, do keep checking for premium gasoline prices on our site and app, it will help you patronize those stations that sell the cheapest premium.