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Better MPG vs. Exhaust Noise

My 2002 Chrysler PT Cruiser currently has a pinhole exhaust leak. Apparently something (reduced backpressure?) matters quite a lot, as my mileage has improved 25%-35%. (I drive like a granny, but it’s never affected mileage nearly as much as this exhaust leak.) I’d just leave the leak and ignore the putt-putt noise …except of course it wouldn’t pass the state (Mass.) inspection.

How can I keep the better mileage while fixing my exhaust?

Exactly where is the leak?

If an exhaust leak were affecting gas mileage 25%-35% I’d have serious resrevations abaout the consition of the exhaust system. The only way I could see this happening is if the exhaust were restricted past the leak.

If the factory exhaust system is as restrictive as you suspect, you could go with an aftermarket performance exhaust system that would greatly reduce the restriction, yet still be legal and able to pass the MA state inspection. Most independent exhaust shops stock performance systems, or can get them easily.

Over how many tankfuls have you checked your gas mileage and what is it? My 2004 gets a best of 20-22 around town and 24 on the road.

Anything altering fuel economy that much on either end of the spectrum should result in some condition that would set a MIL/CEL.

If it’s a valid reading, you have the great advantage of self financing the upgrade/repair. Just drive it, as is, until you have money bulging in your pockets.

I agree, you have made a couple of false conclusions here.

I’d bet that any MPG improvements are the result of you being much more aware of using the throttle because of the increased noise from the exhaust leak.

You’re just driving more conservatively now because of the excessive noise.

It is a red herring. I think you miscalculated now or before.

Are you using the fuel tank guage or actually computing the MPG based on miles travelled(odometer)/gallons pumped.

25%-35% increase…no way…Recalculate.