I wonder where police cars get their gasoline from?

https://lemm.ee/post/1575716

I wonder where police cars get their gasoline from? - lemm.ee

I’ve never seen a cop fill up at the gas station.

It depends on where you live, but a lot of large US cities have their own fueling stations. That way, the city can buy fuel by the tanker load and avoid gas taxes.
Not likely to avoid tax, more to get discount rate on bulk purchase.
If its government going through a vendor they are likely paying more than market rate.
For a like-for-like product or a different service entirely?
“Like-for-like.” I work in state government. Time ago we needed to get some video equipment so had to contract with a vendor to acquire it. They literally just bought it from B&H and sold it back to us.