It's taking 300hp to get 0-60 in 6.5 seconds, and costing 35,000 pounds sterling ($61,000).
42 mpg is just not worth that, even if it could do that on a U.S. gallon vs. an imperial gallon (approximately 33.6 miles per U.S. gallon). My Mazda6 can do a similar 0-60, listing for $28,000 and we'll say gets 21 mpg (usually I do a bit better). At even $4.00 a gallon, that's 8250 gallons, enough for 173,000 extra miles.
Too much engineering, not enough results.