A lot of questions to answer:
How high, wide and long range s the bay you want to convert?
If you need to add on to a bay, do you have floor heat? Will the current boiler support the added square footage? Is this area of floor on its own zone? Will you have
doors?
Can the electrical service support the additional load?
The short answer to your real question “is adding a IBA worth it?” The answer is almost always YES but the costs may be a hurdle for some depending on their financial situation.
I saw your other post about buying an existing wash. Your lender may not be willing to extend you additional credit to renovate a wash that was just renovated and has NO available financials.
Does your personal background include any kind of experience that would make you a good Facilities Manager? Construction Manager? Electrician?
If this is something you really want to pursue you should find a local Carwash owner that is willing to mentor you. The group on this forum can get you pointed in a good direction but you probably need a focused advisor to get everything 100%. Small mistakes are costly to fix.
Don’t be afraid to PM me if you want to talk on the phone,