Giant and Shell Loyalty Partnership: Save up to $2.20/gallon!

There is a new gas rewards program at Shell gas stations in partnership with Giant grocery stores -  details here! Basically, your gas rewards points (earned for every dollar spent at Giant) are no longer confined to just Giant gas stations; you can now swipe your card or type your phone number associated with your Giant card to get the discount - of up to $2.20 off per gallon! - at local Shell stations as well. (Not sure about whether nonlocal Shell stations participate...) As I understand it, every $100 spent at Giant translates to $0.10 off per gallon of gas - and points/savings earned expire after 30 days.

I will be mulling over the details of this and comparing Shell gas prices with those of other stations to determine how this would be worthwhile. In our family's case, our Sam's Club gasoline already goes $0.10-$0.15 less than most, and there's not a Shell station convenient to my usual errand-running routes, so I'm not sure whether I'll use the new program much, if at all.

Anybody else want to comment with thoughts or strategies on maximizing savings with this partnership?