General Motors will start a second shift at its Lansing plant in Michigan from July, adding 600 workers to assemble the new Cadillac ATS sedan.

The ATS is due to be launched in August and will be the smallest and least expensive Cadillac, offering a direct challenge to leading sellers among small luxury cars, the 3-series from BMW and the Mercedes-Benz C-class.

In addition to the ATS, existing production of four versions of the CTS will continue at the Lansing Grand River plant which used to make the phased-out STS.

The new workers will all be so-called entry-level hires on the GM-United Auto Workers union two-tier pay scale. The new hires will receive hourly pay of nearly US$16, compared with about $29 for veteran assembly workers at GM plants.

Second-tier pay is to rise to about $19 per hour over the four years of the deal.

Currently, there are some 835 hourly and 136 hourly workers working one shift at Lansing Grand River.