A set of several automated car washes is selling.

Financially it's probably a wash - you'll have to pay both the agent and the wholesaler.

It's basically a wash, except for the potential implications in self-employment tax but not income tax.You cannot rewrite the past.

I’m curious how time consuming this is (car washes, cleaning, fueling, administration, etc)?

I was thinking of purchasing a used vending machine and running that for awhile.

You can drive for dollars with an app like Deal Machine, you can find properties on the MLS, you can get an agent that knows how to find flip houses, go to a REIA event and connect with wholesalers, public auctions, etc... there are many ways...

Decide if you want a basement mechanical room for the furnaces and water heaters or will these be in the individual apartments.If it's not for new units, maybe take the non-washing  area of the basement and wall it off as you personal storage area for things you may need on site...lock it good, real good with a heavy door, or it will disappear.Good Luck!

If you do decide to take my responses pool side, just be sure you have a stiff drink to wash it down, it'll be more enjoyable. 

A concrete batching plant is a machine that mixes cement and water to produce concrete.

They are different machines and have to be respected, this is where doing the proper due diligence is crucial.