1. Uses less petrol; cheaper to run.
2. Easier to park in tight places.
3. Handles better in wet conditions.
4. Safer.
5. Owner less likely to become phallocentric in thought, word and deed.
6. Owner less likely to end up in porn movie career (not that there's anything wrong with that).
7. Makes the rest of your body look bigger.
8. Makes your legs look longer.
9. Penis less susceptible to feeling cramped when something unexpected arises.
10. Since like attracts like, you may end up with a partner with a small-to-medium sized vagina/anus/car, with all the attendant benefits thereof.

Source: Pandora's Box, Dr Cindy Pan (See Book Review)