My wife insists on naming cars! Our 147 is "Bert", because the last three letters of its registration are EHL. She said she couldn't call it "Ethel" because a) that's my mother's name & b) all cars are male, so she decided it would have to be "Ethelbert", which soon got shortened to "Bert". The 145 was "George" because we bought it on April 23rd, her Peugeot 106 was "Leo".
On our recent holiday we hired a Dodge Charger; as the registration started with BG1 & it was a big car, that was immediately christened "Big One".