Adelaide car component company SMR Automotive (SMRA) will axe up to 140 workers in March in the lead up to Holden's withdrawal from Australian car manufacturing in 2017.
The company said the decision was made due to the downsizing of Australia's car manufacturing industry.
It also resulted from the winding up of a major contract making mirrors for Ford in the United States.
Some 30 of the jobs being axed were full-time while another 110 were contractors.
SMRA general manager John Scott said its 560-strong workforce had been informed of the planned restructure, which would come into effect in March.
"This restructure is necessary in SMRA's transition from being a manufacturer of high volume, more conventional products, to a provider of lower volume, niche products offering new technologies and higher innovation," Mr Scott said.
"Changes to our workforce are a vital part of this strategy and our ongoing viability."
While any reduction in the number of roles at the site is regrettable, the reality is the decision is unavoidable and has been openly communicated to our staff and contractors.
Mr Scott said the company had been forced to modify its business model as a result of Holden withdrawing from Australian car manufacturing in 2017.
"While any reduction in the number of roles at the site is regrettable, the reality is the decision is unavoidable and has been openly communicated to our staff and contractors," he said.
"As a company we must evolve or cease to exist. It's as simple as that."
SMRA said the restructure meant it would remain viable into the future and would "pursue opportunities outside the automotive sector".
It currently develops, produces and distributes exterior mirrors, various interior components and advanced lighting products for the domestic and international automotive industry.
The company said it was pursuing opportunities in a range of non-automotive markets, predominantly medical.
SA Automotive Transformation Minister Kyam Maher said money from the Federal Government's Automotive Transformation Scheme needed to be released to better help companies like SMRA diversify.
"There is just short of a billion dollars sitting in the (Federal) Government's Automotive Transformation Scheme," he said.
"We've continued to call on the Federal Government to release those funds, to help companies diversify out of the auto sector, and also help other industries that will have replacement jobs."