Interior and tech
BMW has listened to the feedback on the M135i and offers a mechanical limited-slip diff (sourced from Drexler and tuned by BMW) as an option.
The cabin in both cars is straight from the BMW gene pool, which means an attractive if unadventurous design and, for the most part, good build quality and finish. The iDrive infotainment interface is also the most intuitive system of its type on the market.
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In the M235i Convertible, the new fabric roof cuts wind noise quite markedly compared to the old 1 Series Convertible, but when lowered the cabin is a blustery place without the wind deflector in place.