Under the Results-button (Autosport homepage) , you can find also the actual racing calendars. But not quite all. I looked for the WEC calendar 2015--nothing TUSC 2015 the same.
But you will find gems as the ALMS calendar, Grand Am Rolex and others from 2013..Superleague Formula from 2011!!
I thought a website should be more up to date..
Michael