Money quotes from Moller's site, and the Milk Farm site :
There are no technical issues remaining regarding the Skycar. Assembling the eight engines and installation is a manpower related issue. Since our staff is presently shared between Skycar engine installation and Rotapower engine volume production it remains difficult to estimate the date of a tether free flight over the Milk Farm lake.
Presently all test flights of the M400 Skycar employ a safety tether from above to protect the vehicle from catastrophic failure. Certainly during these early tests there are a number of failure modes with an aircraft that has 24 microprocessors and 25,000 lines of machine language software code. Additional factors that make a tether mandatory include:
We are test flying within the Davis City Limits
We presently have only one M400 aircraft
Our insurance will go up substantially when the tether is not used while flying over land
We plan to begin untethered flights when we have at least one additional M400 nearing completion. All flights will occur over a specially constructed lake. This lake is part of the Milk Farm development (see www.milkfarm.net), a commercial 60-acre development underway near the city of Dixon in California on Interstate 80. The lake will have an area of 5 to 6 acres and will be approximately 10 feet deep with a silt, rock free bottom. Most flights will occur at less than 50 feet altitude and will incorporate flotation gear attached to the Skycar.
Deposit is refundable until after a successful transitioning flight has occurred. Thereafter deposits are refundable only if Final Delivery Price exceeds List Price (as adjusted for CPI-W) by 5%, OR Standard Equipment List has been shortened OR Guaranteed Performance Specifications are not met, OR FAA Certification Date of the M400 Skycar occurs after December 31, 2006 or a Purchase Agreement is executed prior to FAA certification.The two big technical problems were getting an engine light enough, powerful enough, and quiet enough to do the job, and the flight avionics. By neccessity, Moller had to do some considerable engine development, and have spun-off their 'Freedom Engine', a much improved Wankel Rotary design, as a separate concern.
The first Moller Skycars will be bound by the same rules as conventional aircraft such as Helicopters. The first buyers will be the traditional Billionaire Playboys/Playgirls, and probably some film studios. But as people get their heads round the idea that GPS systems really are good to 10 metre or better accuracy, and if some people who do safety-critical software for a living get involved, then it's likely that we will really and truly have flying cars a la 'Bladerunner' etc. And at 68db noise level, they'll be no noiser than, say, a sewing machine.
10 years ago, when I first heard of Moller, I would have thought the odds of them succeeding were less than 10%. Now I'd put it as closer to 50/50. The key was the engine design. If they can get that to work according to spec, then yes, it's feasible.
And I admit, kinda neat.
UPDATE : Of course, first they'll have to chase off the lawyers.