At present, BMW M has offered modified versions of nearly every BMW nameplate, except for the Z1, 7 Series flagship luxury sedan and the X1 compact crossover SUVs. There is no BMW M version of the 7 Series, as BMW did not want its flagship saloon to be powered by a high-revving engine, and as the recent top-performing versions (usually the BMW 760Li) have V12 engines which while powerful are considered too heavy for a sporty offshoot. So far the unofficial "BMW M7" is the Alpina B7, which is produced on BMW's assembly line though its engine and finishing touches are done by auto tuner Alpina. However, as BMW M shifted to turbocharged engines, there are rumors that there is an in-house BMW M7 in the works, and it is speculated that its performance may exceed that of the BMW 760Li and Alpina B7.