When I need to fill up my car which takes premium fuel, I found an app from Google store that will tell me what stations of premium fuel. You can also get an app that tells you the cheapest gas as well as what stations have a 5 cent off discount.
It's bad enough the way they collude to set the price is exactly the same around bis but the crazy price differences in tiny distances up to more then a doller in places like L.A. is just nuts.