Basically, the answer only matters (and I don't know how it matters) if you are claiming 100% business use of the vehicle. If you claim 100% business use, yet don't have any other vehicle for your personal use, then you "might" be hard pressed if audited, to prove you didn't use that vehicle for other than business use.
Typically for a rental property owner, business use of a vehicle will be less than 100%. So your answer wouldn't really matter. Overall in my experience, I've found that claiming vehicle use for a rental property (I have three) is not worth the effort. The tax "savings" are so minuscule in the long run, I just don't find it worth my time to deal with all the paperwork.
