Using an inverter in the car is very inefficient, as you are converting the vehicle 12V to 110AC and then back to the 19VDC (assuming you are referring to a Dell) required for the notebook. It's also cumbersome as you have to plug in two devices, the inverter and your original AC adapter. And, some of the higher-power inverters can cause problems when plugged into a lighter socket because of the high current draw, such as overheating and damage to the socket or wiring. The lighter/power socket in most vehicles is only rated for up to 10A, which is 120W at 12V. Since the inverter is far from 100% efficient, it will have to draw a lot more than that to produce that much wattage on its AC output. Therefore these are usually best connected directly to the vehicle battery rather than through the socket.
Unless you have more than one AC-operated device that you want to run in a vehicle and you are willing to wire an inverter to the battery, your best bet would be a DC-DC converter which will plug into the lighter and power the notebook directly. These are readily available in 19V applications and they are much more efficient than an inverter.