There has been lots of talk over the last few years about how to encourage overtaking.
I’ve heard from many people the way to deal with it is to reduce aero grip (down-force), and to increase mechanical grip (wider tyres).
Big aero equals disturbed or dirty air behind the cars. Dirty air makes overtaking difficult. Last year the regulations aimed to reduce downforce by 55%, however the double diffuser made downforce a bigger issue than ever.
We all remember the races and overtaking of the 1980’s, and initially this all sounds reasonable but this article http://www.jamesallenonf1.com/2010/03/getting-rid-of-aero-in-f1-the-counterargument/
does give another angle to the argument -manual gearboxes and harder tyres …no seriously, but just read it and see