Vauxhall never got diffs right. You could always tell a RWD Cavalier coming from behind with the diff yowling like a banshee.
Rented a couple of Vauxhall Vectras back in the day. Got backache within ten miles.Mentioned the backache at my chiropracter...she asked if it was a Vauxhall..........................
Astras and Cavaliers gave me terrible back-ache. Especially a Cavalier CDX which had all the lumbar adjustment stuff.
Had two Omegas and I was fine in those. Loved the diesel Omega with the BMW 2.5 TD engine. It had to have an oil service every 4500 miles. That meant I never cleaned it myself. It also came with the ultimate extra - a fuel card. Happy days.