They just need to sort the rear airflow aerodynamics out. In F1 they can't get withing 3-4 car lengths without getting into dirty air.
Lola/Swift/Dallara have all come up with a solution in Indycar called "zero wake" which basically makes it much much easier to get closer to the car in front without the dirty air of F1. Get closer, more overtaking.
And for completness sake, when I said I haven't watched F1 in nearly 4 years apart from the odd highlights, I haven't. Don't feel like I've missed much as whenever you read a review on Autosport or similar its always 3-4 paragraphs of the race with not much happening and then 10 paragraphs of the
pr drone drivers speaking about this new part, or this appeal, or this strategy...... zzzzzzzz
Best thing on a F1 weekend is the GP2 race. They can pass, F1 can't, therefor its the cars. Exepct the last race where they butchered the circuit which last season produced one of the best GP2 races ever while the F1 was its usual snoozefest.