Of course, yes. You can both let the track choose a “seamless” width for the section, and adjust the said width on the beginning or the end of the section.
Actually, the track is a generic container which displays nothing by itself. It just mainly owns sections. These sections are the “true” containers which build, from the coordinates and parameters you gave, some sub-sections which have for each one a road, four walls (back, front, left and right sides) and four sceneries (the same). So, here is an example to get a track section and modify the section width (it is quite Java/C++ style):
self.track = Track()
self.track.addSection(None,100.0,None,None, 0.0,V2(20.0,20.0))
wSection = self.track.getSection(0)
wSection.setWidth(V2(20,40))…which gives…
Anyway thanks for your comments. 