Here is a quick and easy agreement you can sign between the seller and buyer (includes witnesses) of a motor vehicle in Uganda. I know most of us are lazy to draft an agreement, so here is one you can download and print to save you the hustle.
Please note that you still have to go ahead and process the motor vehicle transfer to your names to make it official with the revenue authority.
Plus, make sure to supplement this agreement with national recognized IDs (e.g. driver's permit, Passport, National ID), and a copy of the car log book.
I hope this eases your car deal.