The earliest Holden with the V6 called the VN series , introduced in 1987/8 with the Buick based engine.
This engine went along for several variants and was eventually replaced with the Chevrolet version from the VS series onwards in about 1991/2 as I recall.
My car had the standard engine and transmission (a version of the Borg Warner T5) and the "Sports Pak" option (lowered by 1" , gas shocks front and rear , larger wheels and tyres , upgraded springs , brakes and steering all from the factory.) as well as a limited slip diff , also factory supplied.
One extra change I made was to go back to the standard roll bars front and rear. These were heavier (21mm) dia than the sports version (19 mm dia) since the sports version already had the heavier springs. All this stuff was factory supplied and looked stock so no problems with insurance or roadside inspections. The front roll bar even had a GM part number and bar code taped to it and when fitted to the car it was the first thing you saw when you looked under the front bumper.
Subsequent research revealed the Sports version was simply a "parts bin special" built up from a mix of standard factory supplied components taken from various other cars. The brake system came from the V8. The wheels , tyres and steering from the version designed for Police use. The springs from a higher spec and heavier weight version of the same car and the diff from the unit supplied by Borg Warner from their catalogue and normally supplied for commercial duties.
Loved that car. Had it for 17 years and 496 , 000 klms. Ran faultlessly.
... and dare I say a V8, what about the latest generation Corvettes getting into the 30's.
There are a few other V8 cars that do well. I drove 1600 miles round trip in a grand marquis and averaged 31mpg for the entire trip riding just past 80 which landed the tach at ~1900. There is no way I could have gotten that mileage in the 4 banger tracker I had at the time. Not even if I did 65 in it the whole trip. But, that car had a range it liked to stay in which was no less than 20 and no more than 27. And the 27 tank I'm sure was a fluke because I only got it once.
The Grand Marquis is a fantastic highway cruiser. I will have one someday. My late grandfather's Grand Marquis is still in his garage in Florida. The family drives it when we're down in Florida. When he died the car had less than 3,000 miles on it. The car probably has between 8,000 and 9,000 miles on it now. My uncle took it on a couple of trips to the indian casinos down around Tampa. One of the best things about the car is 80 MPH feels like you can hold onto the door handle and run alongside... Very solid and smooth.