How much power does the average small range wifi router use?

A typical Wi Fi router takes about 100–120 watts. About the same as a 100 watt light bulb.

You can power one in a car if you have one of those adapters that make 120v that plugs into the cigarette lighter socket, but you can’t get any signal into it, because you aren’t connected to the net via cable or DSL.

What? Build a router into a car? Care to explain the use of that? Want to hook up multiple computers in your car and have a lanparty or something like that?

exactly as everyone else has said. you can power a normal router in a car. but to what end. without a connection the best you’ll do is maybe a local network which has a very limited use. Quite frankly if you’re have a bunch of wirelessly enabled computers you don’t need the router to create a local network. Now you could just get something like a mobile stick and that’ll let you get online anywhere you get phone service for the cost of a data plan. That’ll be your best bet for wireless in the car. That and WarDriving but if you’re into WarDriving you’d already know this.