Let me be on record with my intention that the next time I have $4 million in mad money, I am getting one of these babies . Except that I would want extensive modifications. I would want a Bussard powerplant, when such a device becomes available. The Bussard powerplant would produce electricity, so the diesel engines would need to be stripped and replaced with electrical engines. That should improve overall performance, and should definitely improve stealth in the water. Might be good for sneaking up on whales. Or squids. Effectively unlimited electrical power would also mean that the vehicle needs equipment to make oxygen from seawater, which would definitely improve its underwater range.
And, oh yeah -- I'd also want a space drive installed. It is just too bad that the current state of knowledge about dynamics is essentially unchanged from Newton's time, and precludes any space drive that isn't dependent on the rocket principle.
So the space drive would need to be non-reaction-based technology. After all, why would you want a cool-looking vehicle like this spoiled** by being stuck onto a fuel tank hundreds of times larger than the vehicle itself? That requirement may be the deal breaker, because with that in place, the investment is going to be more than $4 million. Always assuming that the laws of physics permit such a thing: centuries of hopeful inquiry have provided not one iota of a hint that it is possible to move in space without applying the reaction principle.
In the meantime, maybe the boat, in submarine mode, could be used to fund the space drive research by being used as a courier for high value goods that need to be moved from production sites in South America to their markets in North America. What do you want to bet that some prospective buyers have just such business models in mind?
** I have similar feelings about many sports cars. Every darn one of them is spoiled by the need to be on wheels. Anything that looks that good needs to float 40 centimeters off the ground.