Turbotax can't properly handle the allocation and I don't think there's a way to get proper results. that's because unless you're using standard mileage for each (you can't mix and match). it's not possible to enter the vehicle on each property and then allocate the expense based on mileage on schedule E directly and if you enter the mileage for that property in the vehicle section depreciation may be improperly computed.
now if you choose to aggregate all the rentals, not sure how this is done (residential can only be aggregated with other residential and commercial can only be aggregated with other commercial), but then the aggregation gets treated as one property so if you only have say residential you can enter all the vehicle info on the first property.
