I PLAN TO TRAVEL THROUGH RUSSIA IN A VEHICLE, WHAT ADDITIONAL DOCUMENTS DO I REQUIRE?

Be advised that crossing Russian territory and touring by vehicle are different things. Here are some Russian car travel tips and the Russia visa information you need to ensure your trip goes smoothly.

Transiting - This means crossing through the Russian territory to get to your final destination outside of Russia by the quickest means possible. Or that your country of destination can only be reached via the Russian Federation.

The visa issuance time is granted on covering 500 km/day on the quickest route through Russia. (You may use google maps to ascertain hypothetical mileage).

Traversing the Russian Federation via vehicle any other means is considered a common Tourist visa, requiring the person to obtain a confirmation and voucher from the hotel(s) or from a registered travel agency that they would obtain from the Ministry of Foreign Affairs.
This would include your travel itinerary and places of stay along the way. In this case, your purpose of travel would be "auto-tourism".