Some designs improve fuel economy and reduce wind noise by having a fairly flat surface but a car with one or more
missing hubcaps is perfectly safe and in the UK, for example, hubcaps are not required to pass the annual MOT (safety inspection).
Even the base car comes with 17 - inch alloy wheels (no more
missing hubcaps for today's teen), and a $ 1,300 upgrade buys cool machined - finish versions.
Not exact matches
If it were an actual
hubcap that was
missing then I suspect it would fail an MoT as it would allow dirt ingress to the hub assembly.