GoKawiilMost vehicles' USB ports won't cut it when it comes to charging a laptop. For example, standard phone charging often starts at around 5W to 7.5W. But the current M5 MacBook Air comes with a 40W (60W max) dynamic charger and needs a 70W or higher USB PD power source for fast charging. Meanwhile, the latest 14-inch MacBook Pro comes with a 70W charger and needs 96W or more for fast charging. Many Windows laptops are in the same ballpark.
You can usually find your laptop charger's required wattage printed on the power brick or adapter. Make a note of it, because you'll need to match it to whichever charging solution you use.
It's worth noting that some newer vehicles, including many EVs, have more powerful USB-C ports that can charge a laptop. But don't assume yours does. Instead, look for a label by the port or a note in the owner's manual that mentions USB-C Power Delivery (PD) or high-wattage charging. If you see that, your car may be one of the exceptions. Otherwise, a standard USB port probably won't do the trick.