lol umm mods? driver? uhh give us some more details. If the cars are running the same specs, it comes down to the driver, but my first instinct would say the 5 series.
i love pointless 'who would win thread.' why dont you google the stock specs on each car and make a logical decision for yourself. things included in logical decision include: hp, torque, weight. Then include in your analysis 4wd vs (cant remember if bmw is fwd or rwd, insert spec here) and auto vs manual. Then throw that all out the window bc if you are starting a AF membership in order to post this thread you are not a good driver and neither is your buddy with the 5 series. Then cry because you don't have a 5 series (my favorite car ever). Then work, earn money, mod your car, repost a thread about how you beat said 5 series because of your new mods.