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How Much HP Does A BMW M3 Still Make After 173,000 Miles?

When we talk about old cars we always reference the power and performance figures that the manufacturer quoted out when the car was new. But how many of those horses are still prancing around 20 or 30 years later,and how many are ready for the glue factory?

 

To find out, Christian from YouTube channel Vehicle Virals headed to the dyno with an E46 M3 he managed to buy for just $3,000 last year.

Obviously, he didn’t buy himself a trailer queen for that kind of money, which if you have seen E46 M3 prices  lately, you’ll know is outrageously cheap. The car had plenty of issues, including the fact it had done 173,000 miles.

Equipped from the factory with BMW’s SMG automated manual transmission, its 3.2-liter S54 straight-six  had been lightly modified with an ECU tune, exhaust headers and performance intake.

In stock form, BMW quoted 333 hp for u.S spec E46 M3  and theoretically the mods should add noticeably to that (the M3 CSL sold in Europe was rated at 17 hp over the standard M3).

But what kind of damage has the addition of all those miles (which we can assume were often very brutal) done? Vehicle Virals’ Christian and his friend suggest 280 hp at the rear wheels would be a respectable figure, which seems to be what M3 fans say you should expect from a stock car in good condition,representing a 16 percent drivetrain loss.

But in fact, the old M3 pulls 290 hp at 7250 on its second run, suggesting a ballpark 350 hp flywheel figure if you assume the same kind of drivetrain losses. As any tuning fan knows, dyno results can vary wildly, but that seems like a decent result given the mileage.

Would a third run yield more? It might have done, but there was so much oil smoke pouring out of the M3’s quad pipes on the second run, the owner wasn’t prepared to take the risk. The dyno numbers might suggest those 173,000 miles haven’t hurt this M3, but the piston rings could be saying something different altogether.