I know that Cessna 182s in Europe have been available with diesel engines for awhile now, but not in the US (that I know of). They would burn Jet A because it's basically kerosene, which is basically diesel fuel.

Seems this has been an optional upgrade since 2008...
WW2 saw some German planes flying with diesel engines... (Junkers) (Deemed not suitable for fighters)
While fuel was cheap, there was no need to use more expensive engines... So why develop a diesel engine for small aircraft (large aircraft needed more power than was easily available form piston engines so naturally switched to turbine engines..
Most of the "downsides" are merely manpower related... The engineering time needs to be paid for, probably none of them are insurmountable... Modern Diesel engines in cars are the example of what can be achieved when the time to develop is invested.

An flight certified diesel has been around for a few years now.
Add several more blades and turn the prop significantly slower will make the plane a lot quieter. The US Army developed a plane that was inaudible at a thousand feet in 1968 and had deployed a "Production model" in 1970.

"a single-engine prop plane that is the first to burn Jet A" - diesel powered singles have been around for years, mainly in homebuild/kitplanes but Diamond were selling the Thielert diesel powered DA40D nearly 10 years ago. There have also been diesel engines retrofitted to certified aircraft.
The biggest drawback is the extra weight caused by the need to withstand higher compression ratios, not quite offset by the reduced fuel burn requiring less fuel to be carried. Another advantage in Europe is that Avgas is heavily taxed whereas Jet A isn't although the additional price of the SMA-engined 182 will offset any savings.

"Modern Diesel engines in cars are the example of what can be achieved when the time to develop is invested. "
You're kidding right? Ever heard of Benzopyrene? All the mainstream automobile and heavy transport industry ever developed and refined in alll these years are toxic spewing engines with horrible mechanical and thermal efficiency with engineered absolence. 2/3rds of the heat produced by your beloved infernal combustion engines are wasted, engines that spin in access of 650 rpms in stoplight doing nothing and acess fuel being burned up in your exhaust just because it's been thrown out. How do you think 'suck sqeeze bang engine' industry make their money? Spare parts. Fuel filters, oil filters, air filters, radiators etc etc Not to mention the engine oil industry.
Check Cyclonepower. They've been granted by the US military to develop small compact generators that can run on any fuel, robots that can power itself by scavenging plants and dead animals/people, susbmersibles that can refuel in under 5 minutes and stay underwater for weeks using their universal fuel 4th generation steam technolgy. They're the next big thing.
On topic, if Cessna is really trying to save the environment, they would've sell converters or offer conversion option instead of selling a new model. The industry is full of greedy people.

Thanks for that info SpaceBagels. Looks good. I just hope vested interests don't beat them into submission too.

@space bagels If you research old popular science(etc,) magazines, most "next big things" are never heard from again.
The laziness of the general population serves quite well as a co-dependent companion to the "conspiracy of greed".
As for aircraft, the nature of bureaucracy in aviation is such that if the FAA had been established prior to the first mechanical flight, the Wrights would probably still be waiting for permission to make their test flight!
"Too dangerous-it's entirely unproven!"

Replacing the piston engine with a small turboprop would surely make more sense, and be lighter as well.

Of course, they could also use a variable pitch prop to increase both take-off and max cruise performance.

re; nutcase
Small fuel efficient gas turbines are very expensive, and have lousy throttle response.