A Betting System for Drivers

Occured to me this morning in cab while cabbie and I discussed which way to take:

There's always more than one way to go to Rome. There's also almost always a debate about which one's fastest.

So why not put our money where our mouth is and bet on it?

It would work like this:

1. I decide to take route a over route b.
2. I tell my onboard computer that I bet 5 pounds that route a is faster.
3. onboard computer tries to find cars in my vicinity that go to same place (or roughly same place)
4. onboard computer sees if any of those use different route
5. onboard computer sees if any of those are betting
6. both onboard computers transfer bets to central server
7. cars go to destination
8. at destination, first to arrive wins money

Now obviously there's some hardware needed in the cars, but I'm pretty sure that'll be around fairly soon. GPS is fairly widespread already, so all we need is inter-vehicle communications. Let's wait a year or so and see...

Or is this a stupid idea?