Fitting a V12 engine into a 2006 BMW 325i is highly impractical if not considered impossible without extensive, if not insurmountable modification to the car's structure, engine compartments, cooling systems, electrical components, transmission system, driveshaft and more components in order to accommodate a more spacious engine like a V12.
There have been few known successful attempts as this conversion remains technically feasible on BMW's higher models like the 7-series or SUVs.
