Yes, the hub is identical
Same 5x115 PCD and same 70.3 mm centre bore: wheels from Cadillac ATS bolt on and centre on Opel Cascada without rings. You still need to check the offset and tyres, detailed below.
≈: width estimated from the original tyre size.
Wheel by wheel: offset and tyres
Each original wheel from Cadillac ATS is compared with the one from Opel Cascada of the same diameter: how much closer the wheel gets to the shock absorber or how far it sticks out of the wheel arch, and whether the tyre keeps the same overall diameter.
- ✓
≈7Jx17 ET42 · 225/45R17 — Fits like the original
Compared with the original ≈7.5Jx17 ET41 on Opel Cascada: shock absorber side −5.4 mm, wheel arch side −7.4 mm, tyre diameter −8.1 % : fit it with the original tyre size of Opel Cascada (235/55R17), not that of Cadillac ATS.
Comparison for guidance only (estimated width). Check in detail
Before fitting the wheels
An identical hub is not enough: offset, width and diameter change the position of the wheel, and larger calipers can touch a smaller wheel. Original wheels often use bolts or nuts with a specific seat: keep the fixings intended for the wheel, with the thread of Opel Cascada (Ecrous - 12x1.50), tightened to the torque shown on its vehicle page. Finally, check that the size is among the approved fitments for your vehicle. This comparison is for guidance only: have the fitting approved by a professional.
And the other way round: wheels from Opel Cascada on Cadillac ATS?