GRJ,
I worded that poorly... I don't think the magnet is creating drag, it's the arm itself holding the magnet. If too much of it contacts the road surface, there's a lot of friction for the car to overcome on the uphill.
The Automotion FX track has a big iron wire inside - much thicker than Faller wire. As such, I imagine they can get away with burying it slightly under the MDF and still have good attractive force; I think Lee actually measured this force in some of his early analysis. In my third pic from the bottom, you can see some of the FX track upside down and one of the actual wires sitting next to my wire cutters (lower left hand corner). Curved sections come with the wire already glued in place. The straights have the wire loose so you can remove it if you need to cut the straight.
I also have some Streets track that I'll be selling 
