Originally Posted by Fanis
Same engines, just different software. Besides power, down are emissions and fuel consumption....it is all part of Marketing.
It's all marketing. 1ER 125i = (2lt) 4 cylinder taxes, insurance, rego etc
In the case of 125i V 328i BMW also changed the exhaust system size on the 125i to detune it, just in case you thought you could achieve the results by just changing the chip or the software.
Fortunately for drivers, there are aftermarket and M Performance options like exhaust systems and M chips to change our already fast 4s into weapons (for those who want it).
It works like this;
Spend money on this model to get more horses and it could cost as much or more as the base model in the higher horse engined car.
EG; add a full exhaust and M chip to a 125i and it will cost nearly as much as a base 135i but have less HP than the 135i
So logic says buy the 135i
However, then your head says 'but I want all these toys included' then it changes the whole game.
My advise; Buy the model you can afford, then if you need more out of it, tinker with it later.