[KeithO]

My wife's car (1995 BMW 525i) has been slowly losing power and having reduced fuel economy over the last 18 months. I rarely drive the car. 2 years ago, it got about 32mpg on highway trips. Yesterday, I drove it for about 150 miles and only got 25-26mph.

It is down on power and very occasionally smells like a morning-after Guiness-fart. I am 90% sure that the cat is shot. I priced OEM replacement cats and every source I checked was in the $485-$500 range (yikes!). There is also the obvious choice of getting a universal cat and making it fit...

How can I be absolutely sure that this cat is bad? I'd like to be completely sure before I commit the time and potential effort on this.

Thanks

[231go]

Beings thats its been a slow process I would do a good tuneup on the car and go from there. Plugs/wires fuel filter, 02's possible, you know the regular stuff and run some top engine cleaner through it and then take it out and flow the crap outa it. Cars that get babied around all day are prone to carbon buildup, so that could also be some of the problem. Beings that its been such a slow loss of power, I really doubt its the converter. Because once stuff starts to break down inside one, it usually goes really quick.