Possibility to run straight 12v for mobile use?

I don't know if this has been addressed before, but I was wondering if, instead of the inverter/power brick setup currently in use for mobile (car) applications, a person could run a laptop off straight 12v DC? Looking at my buddy's laptop the other day I noticed that while the power supply put out around 19v, the battery was rated for a bit over 11v. What would happen if one were to simply input 12v (with the proper polarity) into the DC in?

 

If the '12v' on a car was regulated, it might work. The problem is, its not. The voltage can range from 11v-16v at any given time.

 

I'll have to take a look, but it's not uncommon to see electronic devices that, on the back sticker, have a solid upper line (high limit) with a dashed/dotted lower one when the input voltage is specified. Generally, the low limit is not spec'd but the internal voltage regulator can handle quite a range. That's not to say that the same would hold true for a laptop.
I was also thinking that, especially with a battery that wasn't being charged while in use, that the voltage would not be subject to much in the way of 'spikes'.