Filter View Taxonomy

Hi,

I have a vocabulary like this :

Voca : Auto
-Brand
--BMW
--HONDA
-Fuel
--Diesel
--Gasoline

I want to make an exposed filter in a view but only on the "Brand" Child term.
I can select in my filter "BMW" and "HONDA" but if I add on some term (AUDI, MITSUBISHI ...), these term don't automatically add on in my filter and I don't want to modify my view after each add on (so many term ...).

How can I do ?

Thanks