- will the speed drop when wi-fi?,

[Gdsi <gdsi11@aol.com>]

Good evening.
I  about the wireless Internet. USB modem in the tight car in the parking lot suits, but on the go there is inconvenience, he stick out from laptop in 8 cm, it can be  in the car break it off. His manual says that if plugged he to AC adapter, he can distribute Wi-Fi but I am  wishing  powered his from the car`s cigarette lighter, i.e. from 12 V.  Hence the questions:
- will the speed drop when wi-fi?,
- a big risk to power the modem from car`s charging for mobile phone?,
-If Wi-Fi will bad  distribute, I  make his again the modem but after 1-1.5 m an extension, and his on a clip  into a convenient place?
For any advice, offer,warn, thanks.