I used to have one, they wernt all cosworths although mine was, Ulitima 2.9 V6 Aspirated, made a lovely noise when you gunned it, about 204 BHP from memory, They were all Autos with an Overdrive, if you put it in Sports Mode and floored it, you could actually get MPG Computer down to about 1.7 mpg
, you couldn't really drive too far for fear of it breaking down, as Kevin says normally a Wiring issue, despite it being a Cossie Lump they were heavy cars, a looked after Omega 3.0, 3.2 would give it a good run for its money.
The interior on them was nice, specially the Ultimas, sitting in the back with all that arm chair Black Leather was a nice place to be, people use to fight on mine who was going to seat in the Back.