I would go with adding the garage because I would want you to get the highest and best move on the ARV of the property for that area..

I remodeled the car wash and added new amazing equipment. 

This is why people are getting pissed with cold callers and your seeing very poor response/appointment/sales rates with PS data.This is what Joel Bongco has stated alsoIts absolutely true and I can go further and quantify exactly how bad the data is using my own study comparing PS to county records.I compared PS preforeclosure leads to county records across 167 counties in Texas (67), Florida (50) and California (45) by running searches for both PS ad the County recorders datbase for the period 08/01/2024 - -09/30/2024 and found thatFor TX which i measure preforeclosure leads as all lis pendens, appoinment of substititute trustee (Not a NoD but used for a similar indication) and notice of trustee filings.

.- I posted a recent rehab that I added half a bathroom out of existing space and the comps showed that half bathroom added $50k of value.  

I added value to this property by preserving its original architectural features while modernizing the interior.

Keep in mind, adding "cute", and upgrading things won't increase your rent or ARV past what the market in that area will tell you is the max. 

 (3 convention units +  3 ADUs) * 3 lots = 18 unitsIn general adding one ADU is not a good investment because there is no more expensive residential development than a single, small unit.  

This money gets added onto the back of the loan kind of like a VA funding fee does. 

So suggestion google flat fee broker in your market see if one exits and if your product is that hot negotiate the fee..

A client of mine in Maryland added smart home features to their rentals and boosted rents by 12% with minimal investment.