Except for displacement they have different engine heads (DFI vs MPI), different intakes (have you seen the huge plenums of the F12/LaFerrari?), different internals and of course LaFerrari revs out at 9250 RPM.
Next Bugatti is a conjecture and even if it is a monsterin a straight line it won't be round a circuit. That car is just a dragster.
Efficiency is for Priuses IMHO.
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FERRARI RULES!!!