Development of the insane Devel Sixteen has apparently stalled as those building the car struggle to make it as fast as claimed.

The Sixteen first premiered as a concept in 2013 and made a return to the Dubai Auto Show late last year in what was thought to be near-production spec. The company said it would use a quad-turbo, 12.3-liter V16 engine delivering 5000 hp and be capable of reaching 320 mph (514 km/h).

Helping to bring the vehicle to life was Manufattura Automobili Torino (MAT) but according to Road and Track, MAT is no longer involved in the project. This has caused development to grind to a halt.

It’s probably a lot smarter to buy a Lamborghini, Ferrari, Koenigsegg, or Pagani.

According to a source close to Devel, a plethora of problems are preventing the Sixteen from reaching production. One of these issues stems from the fact that the company has found no way to cool the massive engine for road use. After all, the engine was built by Steve Morris Enginers for drag racing.

What’s more, the same source claims that the Devel team is still unable to design a vehicle that doesn’t fly away once it approaches 300 mph. The source actually says that when MAT left the project, the Sixteen was still essentially acting as a large wing.

Devel claimed earlier this year that it would sell the Sixteen in three different guises. The first was going to come with a twin-turbocharged V8 delivering 2000 hp and priced from $1.6 million. The second was going to be a 3000 hp version with a modified twin-turbo V8. The aforementioned quad-turbo, V16 version was going to deliver 5000 hp and be restricted to track use.