Leds are very sensative indeed, far more than incandecent bulbs. There is no chance of leds causing a spike as they draw an absolutely miniscule amount of current.
They are usually designed for 2v with a max voltage of 2.5v a bit more than this and it will burn out, maybe not straight away but it will eventually dim down to nothing at all.
You could just about double the voltage on a normal bulb and it would still work.
Usually the led bulbs have a resistor for use with 12v, this gives a max voltage of 12.5v so with the unregulated 12-16v and not to mention voltage spikes they will inevitably meet their demise.
Good led bulbs have a voltage regulator in the curcuit but included in the bulb housing itself so that no matter what voltage goes in, a safe 2v is supplied to the led.
I know this as about 8 years ago i changed all the lights on my car to led and they lasted 6 months before flickering, fading away. Changing to regulated leds they are still working today!
Done the same to my Alfa and the first set of leds in my console were not regulated and lasted 6 months.
If you want good led bulbs - www.ultraleds.com
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