For drive-ability it's all about gear ratios. If you have an engine that makes half the torque double the gear ratio or compensate by a combination of lower gear ratio and weight. Gear ratio could be changed via tire size even...assuming you can compensate for it on the speedo.
Z4 sounds nice at 80. IDK if I could pull that off in my car....probably but still that's quite an accomplishment with all that air drag.
280Zs are aerodynamic nightmares, I've heard they can fly at 140+, the hatch seal apparently if it goes bad can REALLY suck exhaust into the cabin (major low pressure zone). I wouldn't be surprised honestly if a Mustang of the same era had a lower drag coefficient. Not to mention examples that don't have rustholes everywhere commend 2-4x more than 280ZXs and 300ZXs do. Kinda like my idea of putting a 4 banger in a Crown Vic to win the MPG challenge...way too much money to be worth it. Even 510s are ridiculously expensive these days.
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If it ain't broke I still want to fix it