Experience
I don't normally drive the motorways in the daytime, but have driven both the M1 and A1M (and A1) in the last few weeks. How many times have I been following someone (on my cruise control so I know that it's not me) to find them suddenly slowing by 10, 20 sometimes 30mph? I've lost count. Invariably they have a phone to their ear when I pass them.
Straw pole from the M1 motorway bridge (my kids are doing statistical analysis at school so it was educational, honest!) on last Saturday afternoon - between 30 and 35% of drivers with a phone in their hands.
We have cameras everywhere - why can't they just devote one days footage over to identifying and fining these b'stards.
To the guys talking about BMW drivers becoming Audi drivers - yes, I heard on a local radio report that an Audi dealer was reporting a rise in sales from people who did not want to be associated with the BMW stereotype any more.
You can identify a BMW owner by looking at their forehead. You'll see the scar from the complimentary lobotomy you get with your first BMW - It's where they remove the 'Cs' compassion, caring, concientiousness, carefulness, etc. and replace it with the 'As' aggression, arogance, etc.