DETROIT (AP) — Whether it be safety systems, fuel economy, engines or quality, most automakers world-wide have raised their games, and differences between brands sold in the US are generally small.

So it comes down to design — the way cars look inside and out — as the way manufacturers can set themselves apart in a wildly competitive market.

"It's the only differentiator left," says Ford Motor Co. design chief J Mays. "If you don't love it, you've lost."

At most companies, the design, once an afterthought, is now atop the food chain as cars and trucks are being developed.

There's no better example than Chrysler's 300C sedan, a blockbuster hit with more than 500,000 sold since its 2004 debut. Its art deco look was different and far more elegant in 2004 than what was then bland competition.

Designers are in a difficult position because they have to anticipate the future, keeping their cars fresh for several years without being too shockingly different. Yet if they're too conservative, their products look old as competitors come out with new vehicles.

"The environment we're in is constantly changing," said Ed Welburn, General Motors Corp.'s vice president of design. "What's hot now maybe its out of step six months from now. It is an incredible challenge."

GM has elevated design so it's considered as vehicles are planned instead of at the end of the process. At Chrysler, the head of design in recent years has reported directly to the chief executive.

Chrysler LLC design chief Trevor Creed said the pressure is on manufacturers to come up with the next 300C, a task easier said than done in a competitive marketplace.

"I think it will become more and more difficult to create that big hit," Creed said in an interview at the North American International Auto Show in Detroit.

Big hits like the 300C are a combination of design, powertrain and price, he said.

"The 300C was the return of the rear-wheel-drive, all-American sedan. Bold looks at an incredibly affordable price," he said. "Pretty soon you've got Kia doing that and Hyundai doing that."