I have a 2001 Beetle which I love, but I also am very happy it's paid for. I replaced the Cat Converter back in 2008 - got a rebuilt Cat, which I had to replace AGAIN at the mechanic's cost that time. Now my CEL is coming on again, showing the code for the Cat. I understand this is an emissions thing, and unless I have an extensive test done, there is no danger to my car and I can keep happily driving it. But someone told me that it could affect gas mileage, which is also very important to me, at 3.67/gallon right now, and I do love to drive. Anyone have any knowledge on this? thanks!!