Evey how many years does Audi and Mercedes change their car design?

[adrianvazquez2006]

you know how the beamer had the 04 5 series and changes the design in 2011?
well every how many years will the audi change its a4
and every how many will mercedes change its C class?

 

[Nick]

A complete change, inside and out is usually every 6 years, while a mild facelift is done every 3 years.