The oil ring groves in the pistons of Toyota 2AZ-FE engines become blocked with carbon.
Service bulletin T-SB-0094-11 contains information to address this problem.
“Some 2006 – 2011 model year vehicles equipped with the 2AZ-FE engine may exhibit engine
oil consumption. The piston assembly has been changed to minimize oil consumption. Use the
following repair procedure to address this condition.”
If it was my car I would try a top engine cleaning treatment before replacing pistons.