The NSX is a mechanical OD so not without adding a device to read it. Other cars you may be able to but they will all be different (theres no standard). When a car is inspected they have to physically inspect the OD for proper milage records. If DMV could do that they would have done it already. Short of a small camera linked to the phone I don't see it being a universal thing. Why would this be useful and to who? Rental agencies?