The 2009 world champion has lacked the pace shown by teammate Lewis Hamilton in the sister car.
Button told Sky Sports News: "For me this year has been more difficult than the last two years. The car is quick, we've proved that on many occasions.
"But for consistency for me it's been a little bit more difficult to get the results. The car next year should suit me a bit more, which I'm very excited about."
The 32-year-old has previously described this year as his worst at McLaren.
The 2012 Formula 1 season continues with the United States Grand Prix this weekend.