The only discount they have now is for earned rewards or cash/debit. And it's supposedly valid at Chevron and Texaco stations too. I remember the 3 cents/gallon discount for Safeway Club Card members when they didn't have any difference in cash credit prices.
https://www.safeway.com/justforu/program-details.html
It's really based on a point system and I guess 10 cents discount per gallon, but can be multiples. They say the rewards are used for up to 20 cents/gallon at Chevron or Texaco, and up to $1.00/gallon discount at Safeway gas stations.