Lol Buttons still the same, but the car and strategies are amazing. :P
I'd go with Nakajima too... He use to crash in T1 or the first few corners every race, now he keeps it on the road and even sets some pretty fast laps.
And Mustafur, it doesn't mean that he's still not at his teammates level that he didn't improve. He improved quite a bit imo. But yeah not many drivers improved. Either the car got better or it got worst, hard to judge... Even if you compare them to their teammates because some cars favor different driving styles then others.