The reason your laptop battery takes 1 hour+ to charge isn't because it's soaking up so many Amp*hours (a unit of energy) but because it has to do it slowly enough that it won't heat up too much by getting charged at too high a rate (energy / time = power). Heat can damage batteries. So you should be ok if you only use your car battery a few times to charge your laptop. Also, if you're using an inverter (turns DC from car into AC for a wall charger, you'll use more energy to charge the laptop battery than if you just use a DC charger your laptop may also have. That's because the inverter might waste up to 40% of the incoming energy turning it into AC.
I also recommend starting your car every couple of days or so and letting it run for a while, maybe even at slightly higher rpm so the alternator's kicking out more amps to push into the car's battery.
I also recommend starting your car every couple of days or so and letting it run for a while, maybe even at slightly higher rpm so the alternator's kicking out more amps to push into the car's battery.