This could be as good as it gets for the US car market

"I don't see the [US] hitting 18 or 19 million," BMW Group head of sales and market Dr. Ian Robertson told Business Insider.

"The US market is topping out at the moment and there's a lot of inventory in the market as well. From that point of view, we see single digit growth this year."

"We don't see (18 million) for this year," Lexus Group vice president and general manager Jeff Bracken said. "Our forecast for the industry is about 17.5 million for this year."

Bracken believes that some in the industry may feel less enthused about the market because we are not seeing the same explosive growth we've seen over the past few years.

"If may not feel as robust, but 17.5 million is phenomenal number," Bracken added.

"Our view is that if our dealers sell one more car than last year, we will be very happy."

"After seeing five years of positive growth, I think it's typical of man kind to start thinking that it can't go on forever and asking themselves whether there's a tipping point and are we there," Porsche Cars North American president and CEO Klaus Zellmer said.

"Our view on this is that there's a potential for Porsche to grow in 2016. If nothing terrible happens to dramatically slow down the economy, we believe our updated and expanded produced line with allows us to grow. We are with good reason optimistic, but it's always good to be cautious and to be prepared," Zellmer added.

"If we don't hit it this year or next year, we won't hit it this decade," Zellmer said. "Because economies work in cycles and if we see a 7 year cycle that's good. But if anything happens to the economy there won't be enough of a buffer in terms of lowing interest rates to boost the economy."