"Regrettably, employers took a very irresponsible stance by pulling back from the engagements which were intended to avert the strike," general secretary Irvin Jim said on Sunday.
"Employers were unhappy with Numsa's decision to issue a 48 hour notice to strike."
Employer organisations, the Fuel Retailers' Association and the Retail Motor Industry have been given notice of the strike.
The strike would see thousands of workers, who include petrol attendants, workers at components retailers, panelbeaters, car and spare parts dealers, fitment workshops, and dealerships down tools.
Numsa demanded a R30 an hour pay increase across the board in all sectors by 2016 for workers earning more than R6 000, a night-shift allowance of 20% of the normal rate of pay, and an afternoon shift allowance of 15%.
Deputy secretary general Karl Cloete said the industry has around 300 000 workers, of whom 70 000 are Numsa members.
A petrol attendant earns at least R700 a week, he said.
Marches have been organised in Cape Town and Johannesburg, and would also take place across the country throughout the week. – Sapa