General Motors is to unveil its new Chevrolet HHR sport utility later this week, but its resemblance to Chrysler's PT Cruiser has already provoked industry criticism.

The bulging fenders, rounded edges and upright stance of both of the four-door vehicles evoke classic American cars from the 1930s and 1940s, distinguishing them from almost everything else on the road.

GM will officially reveal the HHR, which stands for "heritage high roof", at the Los Angeles auto show tommorow. But GM has already released sketches of the vehicle.

Several have been photographed during testing, giving automotive analysts and enthusiasts a good look at the compact SUV.

Many note that GM designer Brian Nesbitt, who lent a hand on the HHR, was the lead designer on the PT Cruiser when he worked at Chrysler.

The retro-looking HHR goes on sale the second half of this year, five years after the PT Cruiser arrived at dealerships.

GM vice-chairman Bob Lutz insisted that the HHR is rooted in Chevrolet history, and recalls the 1949 Chevrolet Suburban.

"One of the things that people say is, oh, this is your version of the PT Cruiser. No it's not," Lutz told reporters at a preview. "If you take a side view of a '49 Suburban and take a side view of this, they are very close to being identical."

GM expects to sell 80,000 to 100,000 HHRs a year, Lutz said. Some will be shipped to Europe, where GM is expanding its Chevrolet brand and the euro currency rate favors imports.