Fourplex with Vacant Lot Next Door

[Jeanne Hink]

Hi,

I'm purchasing a fourplex that includes the adjacent vacant lot (2 separate addresses).  It cash-flows OK and is in great shape.Market rents are about currently $600/month without a garage.  What should I use this lot for, or build on it in order to maximize my cash flow on this property?  I thought about building a 4-car garage; even putting one or two apartments above it.  What do you all think?  

Thank you!
Jeanne