The Verizon IndyCar Series has doubled the number of cars it will have at its disposal for Tuesday's final test for its brand-new 2018 bodywork.

Along with the two primary cars it has used throughout the summer from Chevy affiliate Team Penske and Honda partner Schmidt Peterson Motorsports, RACER has learned IndyCar's visit to Sebring International Raceway's short course will also include a 2018-spec Ed Carpenter Racing Chevy and a Chip Ganassi Racing Honda carrying high-downforce 2018 universal aero packages.

As IndyCar aerodynamic director Tino Belli recently told RACER, the final validation test scheduled for Sebring would be used to sign off on revised brake ducting to cool the new and full PFC braking systems that will outfit every car in the field. New steering wheels, electronics and other components will also be tested on Tuesday.

Ongoing testing by Juan Pablo Montoya for Penske and by Oriol Servia for SPM will continue as planned, and it's believed Scott Dixon will handle the driving for CGR and ECR's Spencer Pigot will pilot its Chevy as his first duty as a full-time driver for the team.

Once all of the bodywork, electronics, and brake systems are delivered, teams will be allowed to start private testing with the 2018 package on Jan. 8.