From bespoke wood veneering, to shimmering hamper sets, opulent accessories are now the growth category in the luxury car industry.

It's helping to double and, in some cases, triple the basic price tag for top-end vehicles.

When you consider that Bentley's latest luxury SUV, the Bentayga, has a base price of $231,825 -- but fully loaded can cost somewhere north of $750,000 -- then you know it's big business.

So luxury auto designers are now turning their attention to the vehicles' trunks to capitalize on the trend.

Unprofitable void

They're pulling together high-end luxury luggage collections to fit snugly into what was once an unprofitable void.

Rolls-Royce spent months of intensive research on the design of its hand-tailored luggage collection.

For a mere $45,854, customers can fill the trunk of their new $320,000 Rolls-Royce Wraith.

That'll buy them six-piece collection that includes two large Grand Tourer valises, three Long Weekender bags and one garment carrier.

Rolls-Royce Bespoke Designer Michael Bryden tells CNN the collection is aimed at people with so much money, they rarely handle their own bags.

"We spent some time at a high-end hotel in Londonspeaking with their head butlers to get an understanding of how customers interact with their luggage," he says.

But while the concierge might be left to grapple with the largest carbon fiber case, the Grand Tourer, customers will still need bags they carry themselves, adds Bryden.

"One very interesting point that came out of our research was that customers will travel with highly valuable items such as timepieces, jewelry and they might want to carry them themselves so as not to let them out of their sight."

Don't forget the car! That custom luggage fits perfectly in the trunk of the Rolls-Royce Wraith, appreciated here by New York socialite Olivia Palermo.

Bryden says the team spent almost as much time on the handles as it did on other components in the luggage collection.

"The handles come together to create quite a large surface area so that you can grab hold of it -- it spreads the weight so that it doesn't dig into the customer's hand," he says.

To that end, the bag has the same lines of invisible stitching that can be found on the steering wheel of the new Rolls-Royce Wraith.

It also engineered the handles for lefties as well as righties.

"Whether you're a left-hander or a right hander, the feel is exactly the same," says Bryden.

Other touches include the same self-righting wheel centers -- with the world-renowned double R marque on them -- that can be found on the cars.

"When we got one of the first luggage prototypes back, the RR was spinning around and we immediately thought 'that just doesn't look right'," Bryden adds.

"We spent a great deal of time taking the mechanism that was on the Wraith itself and scaling that down to make it work on a luggage piece. It's really quite fantastic."

The Long Weekender bags also magnetically dock in the trunk to stop them rattling around when the Wraith is on the move.

(CNN)