Can be done quite easily in SSIS.
See attached SSIS solution which will look through a directory and pop a message up when a xls file is found. All you need to do is adapt that to do the import etc.
My directory structure :
D:\Cities
D:\Cities\Dallas
D:\Cities\Another City
d:\Cities\Dallas\cars.xls
d:\Citiies\Another City\cars.xls
d:\Citiies\Another City\trucks.xls
you could add in further checks to make sure the file name contains truck, car etc before importing.