<mad hair professor voice>
I sink ve hav to tek a step bak unt consider vy a 12v bulb in a 12v systim vould blow, ja?
</mad hair prof voice - can't be arsed anymore>
Filament bulbs go (in my experience of cars, houses and theatre lighting) because they are old (mechanical failure), because they are thumped when hot (ditto), because they are switched on from cold to often (inrush or cold shock), because they are run at too high a voltage (stupidity (110V PAR cans on 240V ...) or badly regulated generator) or because they are cheap sh*t.
The first and fourth don't apply (new 12V bulbs in a 12V* car), but frequent on-offs, thumps and cheap bulbs are still runners?
*Your alternator is OK, isn't it? I ask cos if it were putting out a high voltage, i.e. the regulator pack is kaput or the battery sense wire is broken, then repeatedly turning a cold (low resistance) filament on at an over-voltage would make them pop