Tubbs Pacer is seen in Porto Corsa with other lemons leaders of Hugo, Trunkov and Gremlin. Their big boss shows up on television sets and shows them the accidents of runners during the World Grand Prix. We can see Tubbs smiling and whistling. When Axlerod announces he will not force any cars to run on Allinol, Tubbs and the lemons celebrate their victory. But he gets fast angry when McQueen said he will run on Allinol in London.
That's where we see Tubbs again with the Professor and the other lemon leaders. When Z is intercepted by Holley (who got free as Mater and Finn did), Tubbs says to the lemons they have to get McQueen.
They block the latter with his friends but are rapidly neutralized by Radiator Springs' folks and Tubbs receives a spray department from Ramone. He and the last lemons flee but they are stopped by Sarge accompanied by the British Army.