I know I'm not in a 135i or M-sport but I love my non-power non-leather sport seats. The only stupid thing is nobody understands the seat's shoulder lever to slide the seat forward, they ALWAYS bend down and pull the seat height lever, and with nobody in the seat it springs up about 8 inches and screws up the whole seat position.
That's why nobody touches the drivers seat but me.
Also think about the weight savings on all those motors.
Ordered: 128i Titanium Silver, Black Leatherette, High gloss black trim, Sport Package, iPod Adapter, Premium Audio, BMW Assist