msi cr20 information needed?

I am looking to buy an in car charger for my laptop all for a road trip that will last 30 hours. It is a msi cr620 with a i5-460m intel core cpu.

I would like to know what power (volts or watts) I should get for the within car charger.

Ive looked on the warhorse block itself and there are multiple numbers with volts hrz and Watts and I dont know which one to use.

Any help would be appreciated

Could anyone recommend a good in car charger