Electrical and plumbing all updated within the last 4 years.

For sure PG&E requires this for gas and electric, and I think most jurisdictions require it for water and sewer as well. 

Had a home inspection done and found it needs some work (Roof will need to be replaced in the next few years, some of the electrical needs work, updating the 2 upstairs units, furnace replacement at some point, etc...).  

Are all 4 units metered for gas and electric separately or on master meter? 

Are there separate gas, electric and water meters for each apartment?

I just had a vacancy come up in the middle of a fourplex escrow and the seller had the unit re-rented in under a week for $50/more per month. 6) Yes it's hot, but with individual metering the landlord doesn't foot the electric bill 7) Yes the market is competitive here, but mostly for 3/4 unit properties.

Check w/ the City / County to see what the permitting process is, and what if anything you would have to do regarding plumbing / electrical.

New drywall, mechanicals, windows, electrical, roof, siding- essentially new from foundation up. 

Quote from @Deandre Brown: When analyzing deals, a few additional factors I like to consider are whether the electric and gas utilities are charged per unit or as a single expense.

The entire project took around 3 months with EVERY square in minus the electrical( some added) being gutted and renewed.