From what I can tell, Cessna made about 15 of these aircraft. Also, there seems to be a company doing a C182 diesel conversion via STC, using what I think is the same SMA diesel engine.
While diesel engines have some real advantages, including better economy, the benefits are not as clear as they may look at first glance.
1) Jet A is about 12% heavier than 100LL, GPH is lower in a diesel. However aircraft carry weight, so we must use pounds/KG per hour to calculate economy. Jet A and 100LL have almost exactly the same energy per pound/KG. But not by gallon.
2) Diesel engines are very reluctant to restart at high altitudes.
3) Diesel engines will often flame out (will not remain running) on descent from altitude with the power lever pulled all the way back. This leads manufacturers to set low power limits high enough to prevent flameout, and results in powered descents.
An 80 gallon tank holds 56 more pounds (536 pounds) when filled with Jet-A. While that might not seem like a lot, it's added to the additional weight of the diesel engine and real world useful load is reduced to 1018 pounds total, of which 536 pounds is fuel. With full fuel the diesel 182 can carry 482 pounds. Not exactly good.