Hmmm. Gonna have to look into that. What's your regular gas price?
For regular gas we use our Kroger points as that's what the wife SUV takes.
Diesel I typically save between 25 - 60 cents off regular price.
I found out about these programs when we started looking around for a travel trailer camper. Which actually worked out really nice as I wasn't super thrilled about trying to pull a 35' camper through normal gas stations with all the people and tight spaces. The fact I can pull through a truck lane with wide open areas is a nice perk on top of saving money on fuel.
The popular ones that I'm aware of are Mud Flap, TSD Logistics (Open Roads), and Gas Buddy.
Saving varies from station to station and from day to day, but are more times than not a very noticeable savings. On the plus side the trucker lanes also have DEF (or typically does) at the pump, which is not always very common at the "regular" pumps. The biggest con with the trucker lanes, some can be pretty dang dirty. So make sure you have a rag or gloves.
Hope this helps.