“Winning Key” contests are the scariest of all
I personally have witnessed two “winning key” contests that didn’t go as planned. This mishap didn’t happen to a radio station, but it’s more proof that “winning key” promotions just aren’t worth it. At the end of any big contest you want your qualifiers — your listeners — to feel they had a fair shot at winning the grand prize, with no shadow of a doubt.

The only one who can pull off a winning key promotion like no other is Oprah (remember the Pontiac G6?). In her audience, EVERYBODY got a car. Now that’s foolproof!
You NEVER give out actual keys. Or if you do, they’re dummy keys.
When we do these contests (we’ve done three car giveaways, with nary a hitch among them), we hand out dummy keys. Then the listeners arrive on the scheduled “giveaway” day, and in exchange for their dummy key, they draw a number from a hat. A duplicate set of numbers is in another hat, and we do a reverse lottery (everyone whose number is drawn, loses, until you get to the last number, who wins).
You never, never, never give away actual keys. The biggest reason is, if the “winning” key accidentally gets dropped down a storm drain, then NOBODY can win…which makes your live broadcast on the day of the giveaway, rather uneventful, to say the least.