Have excellent night vision. Won't even need to turn on headlights to drive at night. Can tip them with a hunk of liver or piece of string. Can tell when cat is pleased with tip by pleasant purring sound.
Cats have excellent reflexes, perfect for hectic city streets.
They're neat, and can keep themselves clean all day with their tongue. Won't have to leave cab to go to bathroom. Can keep a small box of kitty litter on front seat for bathroom needs. If they ever go into a high speed roll, cats will be able to land cab back on its four wheels. Names like Mittens, Frisky, and Bailey much easier to remember than those difficult foreign names.