same performance for 08 and 09 models. It's the same car. 2010 model got the iDrive facelift with 10" Nav screen in HD.
If you are concerned about power it is easy to add over 100 hp for under $500 and less than an hour's work.

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Styling: M5 body kit, M5 trunk spoiler, LED Angel Eyes, HID fogs, LED side markers, Jehnert Flatline speakers, Mobridge M1000 DA2 prepro, Zapco Z8 DSP, Zapco Z-150.6 amp, iDock on dash
Performance: JB4/G5 ISO flashed on Cobb, Meth Injection, AR Downpipes, ER FMIC and Charge Pipe, DCI, Walbro LPFP, RB turbos. H&R Sport springs/Koni FSD shocks.