The Bovensiepen Zagato costs nearly four times as much as the BMW M4 it's built on — so we took it to the track to find out if that price tag actually makes sense. Built by the family behind ALPINA, the Zagato starts life as a BMW M4 Competition Convertible (G83), then gets a completely reworked exterior. Zagato keeps the M4's headlights and laser tail lights but replaces everything else with a bespoke carbon fiber body, including the brand's signature double-bubble hardtop roof — a design that only works because Bovensiepen starts with the convertible and deletes the folding roof mechanism entirely. Zagato designer Norihiko Harada led the styling. Under the hood, the S58 inline-six is tuned to 611 hp, with a full titanium Akrapovič exhaust running front to back — and since this is a limited-production car, Bovensiepen was able to remove the particulate filter the standard M4 needs for European emissions rules. The result is a noticeably different intake and exhaust note, with more l...