We've got Speedpass here in Tokyo, too. Just like in the States, it's put out by Exxon/Mobil and you link it to a credit card. Can't use it yet for McDonald's, though.

when you have cards that give double miles for gas purchases, or extra cash back for gas purchases, would you still get those extra cashback or miles if you use a speedpass, i.e. amex giving double miles for gas or extra cash back on Blue cash? Just curious if anyone might know?

Don't know if this helps, but I have my Speedpass linked to a credit card that gives me cashback on gas. I get my cashback regardless of whether I use the Speedpass or if I just swipe my card directly.