There are some laptops that will stop you hard drive from spinning (see here for what lenovo does for example). This is to prevent the hard drive from potentially colliding with anything while moving at high speed.
HP offers a similar utility.
As for how useful these features are, I have been unable to any research on the issue, but the premise is sound. When some amount of instability is detected, move the read write head to somewhere where there is no data. That way, if there is a collision, you have a lower risk of losing data. The HD may still be toast though (i.e. if the head hit the unused section of the drive, it may be totaled, but you data will be fine). This reason is in addition to what is above.
In short, I don't such a feature is necessarily by any stretch when using a laptop in the car. Hard drives spin (SSDs don't have any of these issues, and are therefore much more durable) very quickly, and already have to account for things like bumps (at least on a millisecond scale). The difference that this technology makes is when the whole laptop falls, or something of similar magnitude.
With regard to overheating, all of the regular rules apply. Make sure there is enough space after the vents to allow the hot air to dissipate (10+ inches to be safe) and don't cover the vents on the bottom.
As an aside, it is not about getting a good enough cable to connect it to the car, but rather making sure your charger does not draw too much power.