It was a BMW 530d test car although the Benz E-class E280 felt better overall ... The Benz S-Class S350 test car I drove kept up with the Subaru Impressa WRX test car through the twisties with some audible protests from its huge tires because I was trying to keep my momentum up through the corners.
I also did (unintentionally) drift out the rear of the BMW X5d but it was a slower speed at 110kph through the same corner because of wet road conditions (water puddles at the apex of one curve) and I didn't have the guts to turn off the traction control. hehehe