Some of the very rich like to go further than just displaying their wealth. They want things that few others can have, such as vehicles like an armour-plated SUV.
And now there's another extreme machine aimed at the moneyed motor-mad: the EV2.
"It's a luxury, high-speed vehicle," explains one of its makers, Mike Howe.
"You hit a button and the gull-wing doors pop up just like a Lamborghini. Inside you have eight-way leather seats, reverse camera, cameras up top, state of the art tracks, state of the art suspension..."
In fact, according to Mike's twin brother Geoff, the EV2 is a "luxurious tank". That's because the machine has tracks like a tank, rather than wheels.
The brothers claim that, thanks to its tracks, their vehicle can move at high speed across all kinds of rugged terrain in a similar fashion to its military counterpart - but unlike the latter, the EV2 is devoid of armaments.
They say that there is demand for the product. However, the luxury market is a new departure for them, and a far cry from their normal line of business.
The brothers trace the origin of their enterprise (based in Maine, in the US) all the way back to their childhood.
"We were always pushing the envelope," recalls Geoff.
"We built our own log cabin because the other kids down the street had a tree house that their father helped build. Mike and I didn't have a father figure at the time. So we had to do it on our own. We wanted to make it bigger, better."
As time passed, they graduated from log cabins to unusual vehicles, such as off-road racers.
In their college years, they converted a tour bus into a mobile stage for their rock and roll band.
Later, they became obsessed with the idea of building an extremely fast, tracked vehicle. After years of work, they ended up creating a small tank, which they called the Ripsaw.
The device caught the attention of the US Army, which eventually ordered manned and unmanned versions for research and development.
As a result of the US military's interest, the brothers were able to turn their hobby into a business.
The challenges they faced in creating the Ripsaw were formidable.
For example, the faster you try to make a tracked vehicle go, the more likely you are to lose a track. "It's like a wheel coming off on a car," explains Mike.
Engineering problems like these proved tough to solve. The brothers looked beyond the automotive world for answers, and took lessons from elsewhere, such as from the technology employed in chainsaws.
As they gained experience, they expanded their range to include products like robotic systems that could help to disable bombs, and the Ripchair, an extraordinary off-road wheelchair with tracks.
Hollywood also began to take an interest, and the brothers' vehicles have appeared in several big-budget pictures, like GI Joe 2 and Mad Max: Fury Road.
It was collaboration with the movie industry that led to a new direction for the business.
One day, the brothers received a call from someone working for a wealthy individual who had seen one of their vehicles on screen, and wanted a bespoke leisure version of the Ripsaw.
They were at first surprised by the request, but after careful consideration, they decided to give the idea a go. The result was the EV2.
They find dealing with the luxury market a whole new challenge.
"There is a learning curve," explains Geoff.
One of the biggest difficulties is establishing clear lines of communication. He is rarely able to talk directly to the end client - so it is vital to ensure that the customer's wishes are being met, rather than those of any intermediaries.
The brothers have found that clients in this market are interested in a range of options.
In addition to those already mentioned, they include a night vision and thermal imaging system, which displays images of the road ahead and around the vehicle.
"You can shut all the lights off at night and the vehicle is completely dark and you can run 60 miles an hour down the road and see everything you need to see to be able to drive safely," says Mike.
He adds that it's up to the client to establish where and how the vehicle can be driven safely and legally.
The high cost of EV2 (a typical model costs hundreds of thousands of dollars) presents another challenge.
Because so much money is at stake, the brothers sometimes need to do some delicate checking on potential customers, to establish that they are able to afford the cost.
They say they have enjoyed adding a "luxury" product to their portfolio - but they do not want it to end up skewing the direction of the whole business, which is why they see it forming only a small part of their range in future.
This approach is wise, says author and consultant Peter York, who has advised many large luxury enterprises.
"If you start spending time on billionaires' private fantasies then there are immense opportunity costs.
"A technologically innovative business and a luxury business are very different," he says.
'Pushing the envelope'
Still, the brothers are always open to new ideas, and for a special client, they will continue to push the envelope.
At present they are working on a variant with 2,000 horsepower - nearly four times the power of a standard EV2.
"We have no idea how it's going to work out," says Mike Howe. "We're riding that edge between what's physically possible and what's a dream."