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I noticed that the fuel economy of the TSX for 2010 with a 6 speed manual is 20/28, however, the 2011 6 speed manual is 21/29. Did they actually change anything or did they adjust their ratings to more closely resemble what people are actually getting?

09TSXTech

Improvement were made to the engine to reduce friction for 2011.

Below is from Acura newsroom:

The most significant change to the TSX powertrain for 2011 is the use of numerous friction reducing technologies applied to both the 2.4L I-4 and the 3.5L V-6 engines. The reduction of internal operation friction enables the two engines to deliver improved and class-leading fuel efficiency.

Both the 4- and 6-cylinder engines make use of a new plateau honing technique for the cylinder bores that generates a smoother surface. As a result, the piston rings achieve more consistent contact with the cylinder walls which generates improved ring-to-bore sealing along with reduced overall friction.

With the 2.4L I-4, the pistons make use of a new low-tension piston ring that reduces operating friction while the 3.5L V-6 uses a redesigned ion-plated piston ring design. In addition, the outer skirts of both the 4- and 6-cylinder pistons now feature a molybdenum coating applied in a unique dot-pattern application. The result is reduced overall friction as the pistons move within the cylinder bores.

Other friction reducing items include the use of lower viscosity engine oil (0W-20 weight versus the previous 5W-20 weight oil) along with lower viscosity oil for the Sequential SportShift 5-speed automatic transmission. In addition, the 5-speed automatic fitted to the 2.4L I-4 engine now makes use of a new fluid warmer assembly warmer that helps improve shift quality and engine fuel economy for TSX owners who live in colder climates.