The car is called Bernadette (BMW 318ti) it's predecessor was called Bertie (BMW 316i), as the newer one was a lighter colour so looked more girly it changed gender, and Bertie as it sounded posh and it was my first step into bmw ownership.
Motorbike is called Kayla, as it's a tart of a thing bright orange zx6, kind of made me think of Kayla Collins.
Yes as you have guessed first letter of brand is the first letter of name.
Bicycles all have names as well, Candice the cyclocross bike (Cannondale SuperX), Charlotte the mountain bike (Cannondale M900, it's bright yellow, and was rhymed with Charlotte the bright yellow harlot)
Think that gives you folks enough evidence to convict me of being a nutter.