I would guess that the Miata
I would guess that the Miata will sustain it's numbers without a problem. However, being an old Fiat 124 fan, having owned a '72 Spider from new for 6+ years WITH NO PROBLEMS, I have a secret desire for the Spider to do VERY well. And from what I've been gleaning from reports many who try both like the Fiat better including a few who opted for the Miata and are looking to change.