Volkswagen's US unit plans to triple its product range in the fast-growing crossover segment and refresh models more quickly, company sources have said.

The campaign will include a five-seat variant of the forthcoming midsize sport-utility vehicle (SUV), previewed by the GTE concept unveiled on Monday at the Detroit show, the sources told Reuters.

VW is also stepping up cooperation with dealers and assembling a team of 200 experts in R&D and design at its US plant to ensure vehicles better cater to American tastes.

"It took us long to realise that the US market requires more special attention," a senior manager at VW's German headquarters told the news agency on condition of anonymity.

"You have to have an ear on the ground to capitalise on trends and customer desires."

Michael Horn, VW's new US chief, has reduced the product lifecycle from seven to five years for sedans and is planning similar changes for SUVs, a source said.

"It's the game you have to play in the hype-heavy US market," the source said.

VW's past failings mean it will miss an 800,000 US sales target for 2018, according to researcher IHS Automotive. It sees 547,000 sales of VW-brand cars by then, from last year's 367,000, missing the goal by about a third.

Chief executive Martin Winterkorn, at a reception in Detroit on Sunday night, admitted it could be tough to more than double US sales to 800,000 ‎by 2018. "This will not be a walk in the park," he said. "We are facing challenges in this great market."

IHS forecasts include VW's plans to overhaul the Tiguan compact SUV this year plus a coupe-style version and long-wheelbase model that may offer a petrol-electric hybrid option.

A source at VW said the new long-wheelbase Tiguan seven-seat SUV is most likely to be built in Mexico in 2017. The five-seat Cross Coupé concept SUV unveiled at the show is likely to be assigned to the Chattanooga plant, the source said.

US compact SUV sales rose to about 1.49m last year from 964,000 in 2009, while midsize SUVs grew to 1.69m from 946,000, according to auto website Edmunds.com.

But VW won't benefit from the boom until new products arrive in 2016-17, Evercore ISI analyst Arndt Ellinghorst told Reuters, noting that existing Tiguan and Touareg models cost more than rivals.

Also, Toyota and Mazda, buoyed by the weak yen, will keep pushing into passenger cars, VW's traditional area of strength, he said.