Ok, short tutorial...
On frontview, create a rect. As wide as your track should be.
Move it as far away from the 0/0/0 point, as wide the curve(?) should be.
In object-mode, revolve that part. 360deg. around the Y axis. I used 26 element revolve, so we get two sides which are parallel to an axis. (See top and bottom edge in top-view, following picture)
In vertice-mode, select half the circle...
...and move it away
Select the outer top vertices...
...and move them straight up
Finaly an Indy-like racetrack...