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Damonzero 5 Series E60 525i (Gun Metal Grey)

Depends on which year.

If its manufactured after 2005 it most probably has the n52b25

If its before 2005 it most probably has the m54b25

If im not mistaken the m54 has better fuel efficiency

But the Magnesium engine has a higher BHP output 

n52 is a Normally Aspirated engine which is "Normal"

while the n54 is something like a performance Engines with Turbo's
Better depends on you, do you want better fuel efficiency or higher BHP output? 

The 525i never had the n54 engine to begin with.

The latest engine the 525i ever had was the n53.

Hope your not confused

the 525i at one point had a 3000cc engine with the n53. Just once.

The rest are 2500cc

the 525i at one point had a 3000cc engine with the n53. Just once.

The rest are 2500cc

Both n52 and n54 have 3000cc ENGINES

n52

&

M54

I already stated that in my first reply.

525i changed three engines during it's lifetime. At first it used the old M54B25 which was replaced by N52B25 in 2005. Last three years of production the 525i used newest N53B30 engine which produced same power at lower revs and more torque.

Depends on you.

Save Fuel go for m54, want power? go for the newer magnesiums.

What I meant is continuous repairs. Like electronics parts for the e46

i want to ask. For new BMW, it is stated the warranty is 3years @ 60K mileage inclusive service and repair. Does it means we dont need to pay anything else except car installment? regular servicing and eth.