Conclusion
When all is said and done, rather than relying on the possibility
of an upgrade or vehicle change at the car rental counter,
you really are best served by planning out everything in
advance. This particularly is the case if you are particular
about the type of car you end up getting when you are going
to a car rental agency. If you are not so particular, there
are instances in which you can save money and obtain some
other benefits by waiting until you get to the car rental
counter to try and get an upgrade or make alternate vehicle
selections.