Just had my 1997 Mazda 626LX 2.0L 4 cylinder coupe smogged and all the numbers look great except for the NO(PPM) at 15MPH. The Max allowed is 467, average is 57 and I was 230. So I passed, but want to know what this might signify. At 25MPH the max NO(PPM) is 754, average is 50 and I was 4! Could they have gotten my measurement wrong or is it possible that from 15 to 25 MPH the results could be so diametrically opposed? This car only has a bit over 22,000 on it and I'm driving it maybe 1000 miles/year. Haven't had it looked at for quite a while.