BMW and Alpina tag-team on Bavarian bruisers at NYIAS

You wait an age for a stupidly-powerful, ridiculously-luxurious, vast Bavarian sports sedan, and then two come along at the same time. Sharing the spotlight at the New York International Auto Show today are two takes on the same car: BMW's tech-blessed 7 Series. On the one hand there's Alpina's 2017 B7, an independent take on the high-end sedan. On the …