It's a 4 metal building storage facility with a total of 24 storage units that rent for $600/month each.

The property is storage units. 

Any opportunites to add value like storage space you could charge for, pass the heat or sewer costs on to the tennants, are rents below market? 

Self storage...he just had an offering a few weeks ago.

I have the opportunity to purchase a 4-plex with a 1500 sqft storage building that was abandoned a few years ago. 

Storage?

Perhaps it’s big enough to build a small self storage building on ?

I already know that a clean nice lit storage area would be a great upgrade, and we plan on doing that to the basement, after we paint over the graffiti/etc  https://www.realtor.com/realestateandhomes-detail/...I appreciate it! 

A roll-away center island might help with storage and give additional working counter space.

Also, I don't know the formation of your driveway and garages, but I have maximized my parking by actually blocking to garages with three cars parked perpendicularly and then renting the garages for storage.