Obviously one of your chief concern is gas mileage, and both do tremendously.
My suggestion is stick with German...the TDI is a solid car, and worth it.
'09 E93 DCT M3 - Jerez on Ext Blk Nov w/Carbon Leather Trim
Custom Tune, OEM Perf Mod, MS Stg 2 Intake, GTS DCT/Euro MDM - MR Hood Vents/sidemarkers, H8 160, tinted tails, Gloss black kidneys w/metallic M fins, V1
WTB: E93 LCI Tails w/harness - Driver heated mirror - Exhaust tips - Driver Door Panel