Justin is right, but I'll go one farther:

Even if it burned avgas, these are not "consumer" prices. They are not meant to be.

These prices are for "corporate" consumers in a non-US environment. This is the same as pricing/concept as you'd see for military/commercial grade hardware.

A similar-ish example:

I've been going to an event (DragonCon, in ATL) every year for the past 15 years or so. Same place, same time. I usually spend about 1 AMU for the hotel room (5 days), plus another 1 AMU on other stuff. Good times, lotsa laughs, meet cool people.

At some point, a "big league" college football whatzis started their little game thing on the same weekend (needless to say, I'm not much of a sports fan...I don't even know which end of the rink the hoop goes on in baseball). Rooms started getting to be harder to get during that week. Last couple years, there's been two games, and rooms have been a challenge to book (and price has gone way up). This year, there is a third in driving distance.

Rooms are now impossible to find, at any price. In the past, you could get rooms close in to the date, because people would cancel as they figured out they couldn't go. Now, you've got high dollar corporate interests buying entire blocks of rooms, which don't get cancelled, even if they don't use them.

Sure, the "my" event was there first, but they got essentially muscled out by the football thing. You just can't repel firepower of that magnitude.

My point, in obviously a very round-a-bout way, is that sooner or later, the little guy gets squeezed out. Cessna, IMHO, never intends to sell any Diesel 172s to the end user at 400k+.

Best,
Rich

Here.....here....lot's of people think nothing of dropping $100K to save a few gph.

I did it once. I took a 172 from Chicago to Denver mostly for the heck of it. Round trip (18 hours) over a weekend. I had a blast!

Yes. HP = torque at a certain speed. Most diesels run at lower RPM and produce more torque thus can spin a higher pitch prop and make more thrust with less RPM. Also, this plane has a constant speed prop. That alone makes a noticeable difference compared to a fixed pitch.

HP is really only a useful measurement at 5250 RPM (the point where it meets the torque curve).

It's somewhat different in cars because of transmissions (convert between torque and RPM) and because cars don't usually have a low, fixed RPM limit. In airplanes, the RPM limit (aside from engine limitations) is based on the speed of the tip of the prop. Above .8 mach or so, they loose efficiency very quickly. Basically, the slower a prop is spinning, the more efficient it is.

Therefore, a high torque, low speed engine is PERFECT for an airplane. The only real historical problem with diesels was that they were heavy for the power they make. Recent improvements in metallurgy, machining and turbochargers (these have improved MASSIVELY in the last 20 years, even more in the last 10) have changed that landscape significantly.

Comparison:
Continental IO 520 - 280 HP @ 2700 RPM = 544 Ft. Lbs torque 484 lbs.
Audi 4.2 TDI - 303hp @ 2700 RPM = 590 Ft. Lbs torque 562 lbs.

The Audi weight is including accessories, the Continental is without. In a real application, I bet they'd be very close. The Audi is also capable of making 345hp @ 4200 RPM. With a 2:1 gearbox, that would be a 2100 RPM prop and a full 345 HP, but with the weight penalty of a gearbox.

When Continental or somebody else releases a 300hp diesel STC'd for the Bonanza, I'll be the first in line to buy one.