Most vehicle recalls are not of the form: return your vehicle, we give you a new fixed one; but rather: bring your vehicle to one of our dealers and they'll perform some action to repair the defect.
The later is pretty analogous to issuing firmware and OS patches to mitigate the flaw.
What if the fix to the car reduced your MPG by 30% to address a safety issue? This seems somewhat analogous to the number being bandied about as the CPU performance decrease. (Depends on workload, etc, etc.) I think most car owners would expect some kind of compensation for a product that no longer has the same efficiency as when they bought it.
This issue is similar to what happened with the Volkswagen emission cheat. After they fix the ECU to have the advertised NOx emissions, the car lost peak power and fuel efficiency.
The later is pretty analogous to issuing firmware and OS patches to mitigate the flaw.