Current and accurate vehicle odometer reading (vehicles less than 10 years old must have both parties' signatures and hand printed name of sellers and at least one hand printed of the buyer, per Federal Law).
To create joint tenancy with rights of survivorship, there must be specific language declaring such intent, signed under penalty of perjury in the second degree by all owners. DR 2395 Joint with Right of Survivorship (JTWROS) (PDF) is only applicable to multiple owners and must be signed by all parties.
Proof of insurance.
The current title or documents from the dealer properly endorsed by the previous owner(s). Signatures must be notarized if the title has a section for notarization. Do not purchase a vehicle from an individual(s) without obtaining a properly assigned title.