Drew the track was closed at the start of WW2 and became a aircraft factory for the war effort. It never re-opened as a track. Very little of the original track remains. Some of it was destroyed by Greman bombing. One part of it is now a housing estate!
However presenter James May from Top Gear managed to recreate the full length Brooklands using Scalextric track and cars.
This was undertaken with a team of 350 volunteers building the track from an uncounted number of pieces of Scalextric track, navigating ponds and roads, closely following the route of the old Brooklands track. This event broke the Guinness World Record for the longest ever Scalextric track in the world, intended to measure the original 2.75 miles (4.43 km) of the original Brooklands circuit but in reality recording 2.95 miles (4.75 km) in length (due to the need to navigate modern features that block the original course). The episode was shown on BBC2 on 17 November 2009 as part of James May's Toy Stories.
http://en.wikipedia.org/wiki/BrooklandsIf you look at the track on Google Maps or Google Earth you will see it's current condition.