I got a bug up my ass and finally installed a pair of roof vents in the garage. Our hot Chico summers, combined with minimal venting of the garage, meant for hot temps. So much so, that garage work would suffer. I thought about a powered gable fan, but after looking at my gable area, I realized there was too much framing in the way. So I settled for a pair of whirly gig spinning passive vent things, as shown below.
I bought two kits, roughly $31 each.
crawled up on the roof and set out the tools:
Cut out a hole:
Both vents installed, and spinning away. Inside garage temps are 10 degrees cooler this afternoon compared to yesterday afternoon, and it is only in the 70s.