Hi,
Have used a Ford Escort with one. There are no visible filaments,the screen is exactly the same clear shade as one without the heating elements. They are fabulous. In icy misty conditions they clear the windscreen remarkably quickly.
Mind you, given the Micky Mouse electronics on the MINI, you will probably get 2,000 volts through your backside each time you turn it on. That, or cooked gonads from the heated seat.....
Cheers
Marsh: