User blog comment:Na299/Ways of Gold Farming/@comment-99.251.150.111-20150526132900/@comment-87.128.228.130-20150526134847

so, when you employ the gold harvesting, you go from driver level n to level n+1. Now, if you manage to earn so much fame during a continuous harvesting that you go from level n to level n+2, then you are rewarded with the gold for 2 level-ups. That's the "multiplication of the level-ups".

Whether you can get as much fame or not, well, check out the description of the challenges you have open at the moment here on this wiki and try to calculate whether you can get enough fame. I started to apply the Agent for all races I had to win during the SF challenge and it worked out.