Scalextric advice is"Ideally, it is best not to nail, screw or glue the track to a base board at all. The reason for this is that plastic and metal, the two ingredients of Scalextric track expand and contract at different rates. So, on hot days the plastic will expand larger than the rail. Of course, the rail won't let the plastic expand evenly due to the rail gripping the plastic. This causes the track surface to warp.”
However if you want to tip the track on its side it needs to be fixed, so we used Scalextric C8232 track fixing clips, with Hornby R207 Track Fixing Pins
We found that because MDF has a hard surface it was necessary to drill a small hole before the pin could be nailed in.
We also found that the digital track is slightly thicker than a standard piece of track, so it was necessary to use packing under the clip (see below) on these sections. It was also found that it was easier to cut the border around the clip, this is then covered by the rumble strip.