I notice the driver is the same level as the level cap of the manager, so progress will slow to 1% per session.
See this post for more information:
http://igpmanager.com/?url=forum-thread_2/5613#42441
You might also be interested in this post on proposed changes to level caps, which would open up faster training on this driver again:
http://igpmanager.com/?url=forum-thread/5699