The Tasmanian secured the title with a second-place finish to a dominant Joel Heinrich (Chevrolet Camaro) in the final round held at The Bend over the weekend.
Garwood had entered the event with a commanding points lead over Ford Mustang driver Jamie Tilley but endured a scare on the opening lap of Race 1 when he clashed with Andrew Fisher and spun to the back of the field.
The Commodore driver recovered to sixth in the opener before taking second place finishes in the second and third heats, celebrating the title with a series of donuts.
It marked a big result for the versatile driver, who has raced a variety of machines in TCM over the last decade, as well as other classes including Trans Am, GT4 and Carrera Cup.
The Garwood family bought the Commodore from previous owner Lucas Dumbrell in mid-2023 and it proved the class of the field this season, capping a five-year journey for the machine in TCM.
It was built for the class in 2019 by Gerard McLeod, who had long campaigned for the early model Commodore to be eligible for the category.
Once given the green light, McLeod bought the one-owner road car from a farm in Daylesford, Victoria, where it had sat dormant for 15 years.
McLeod debuted the car at the 2020 Adelaide 500, resplendent in a livery paying tribute to the Autopart Centre Group A Commodore his father raced in 1986.
The now title-winning TCM Commodore is prepared by McLeod’s Maverick Performance for Garwood and still runs the tribute livery.
TCM’s season finale took place as part of the weekend’s 777 Endurance event that also featured a dramatic end to the Australian Prototype Series.
Title contenders Jason Makris and John-Paul Drake both spun at the first corner of the finale. Makris recovered to seventh – two places behind Drake – to hang on for the series win.
Miles Lacey (Praga R1) took the round by just two points over Drake (Wolf F1) with Phil Hughes (Radical SR8) third and Makris (Wolf F1) fourth.
The Excel Enduro – awarded from combined results of 2 x 60-minute races – was won by Ethan Grigg-Gault and William Sala.
Supercars drivers Thomas Randle (with Charlie Nash) and Tim Slade (with Fletcher Lewis) were fifth and 20th respectively after the latter failed to finish the second race.
Combined Sedans weekend honours went to Toyota 86 driver Michael Bartsch, while the 777 Enduro was won by Commodore VF trio Dale Carpenter, Joel Stafford and Troy Gleeson.
The winners completed 59 laps of the 7.77km Bend GT layout in the four-race race, which featured 11 starters across three classes.