The Mangusta got the same 4.6 liter engine made by Ford that was used in the Mustang Cobra. It made 305 horsepower, and in the Mangusta (which is lighter than the Mustang Cobra), it was able to propel the car from zero to 60 in about 5 seconds.
One thing going against the Qvale Mangusta was the price. It was about $70,000 brand new, which in the United States would be about the price of a Dodge Viper at the time. The Viper had more power and more size, and thus made a better status symbol than the peppy little Italian roadster.
The MG XPower SV was derived from the Qvale Mangusta, so though this car failed it still lived on in the form of a very rare car (63 produced) from 2003 until 2005.
These Qvale Mangusta cars are very rare. They only made a total of 272 of these in their 3 year lifespan. If you want to buy one, there are a few places to look. I'd actually look on eBay first, then maybe Hemmings.