Yes, the hub is identical
Same 4x100 PCD and same 54.1 mm centre bore: wheels from Aston Martin Cygnet bolt on and centre on Fiat 124 Spider 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 Aston Martin Cygnet is compared with the one from Fiat 124 Spider 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.
- ✓
≈5.5Jx16 ET45 · 175/60R16 — Fits like the original
Compared with the original 6.5Jx16 ET45 on Fiat 124 Spider: shock absorber side −12.7 mm, wheel arch side −12.7 mm, tyre diameter +2.5 % : fit it with the original tyre size of Fiat 124 Spider (195/50R16), not that of Aston Martin Cygnet.
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 Fiat 124 Spider (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 Fiat 124 Spider on Aston Martin Cygnet?