[smileysteve]

The radio wave is sent from a remote to a surrounding area though.

IF many cars were on the same frequency, any time more than a few dozen people (think after sporting events) it could easily be possible that you'd get one of these delays; if you get it, and press it again you start the timer over for every car in your rf range.

Also, think of the issue @ the dealer.

Now, if two hashes were sent, the vehicle address and the next security hash, then this lockdown mode works.

[gnaffle]

This is easily (and almost certainly already) solved with pairing the key to the car, so that the car can safely ignore any unlock attempt by another (legitimate) key.