i would keep the a4 as long as it has the 2.8 liter engine. Add a pes supercharger kit to it, and you get almost to 300 hp and it will out perform the lexus and keep its value longer to. go to
http://www.pes-tuning.com/oldsite/index.html to check it out. but if you realy want a new car i would go with infiniti G35 coupe 280 hp very slick, 6 spd starting from $29,000 defenatly better then the lexus, and has style.