The Volkswagen Golf and GTI were completely redesigned for 2015. The GTI reached dealers first, and to date few repairs have been reported for it. The Golf with the 1.8T gas and 2.0 TDI diesel engines has not been so lucky. With this month’s update it looks like they’ll have reported repair frequencies in the 50s (per 100 cars), more than double the 22 for the GTI. (The GTI’s rating is exactly equal to the average for all 2015s.) What’s going on?

I don’t know. Looking at the repair reports, the only problems we have multiple reports for are AC compressor failures and an audio system that changes stations when turned off then on again. There’s a free software fix for the latter, so it doesn’t count in our stats. At any rate, both problems affect all three engines–they’re not powertrain-specific.

Our sample sizes for the 1.8T and TDI still will be a couple short of the minimum–they’ll have asterisks for “small sample size.” But if they were combined for a “non-GTI” stat the sample size would be a healthy one. And with the next update the scores will both be similar, so a combined stat would also be in the mid-50s.

What’s more, Consumer Reports recently updated its stats (based on a survey conducted last April, so the same time period we covered with our May update), and they are reporting the same difference, with the GTI rated “about average” and the Golf rated “much worse than average.” Looking at their system scores, the Golf actually has a better rating for noises/leaks, but a slightly worse one for fuel system. However, even the latter is half-red (good). None of the Golf’s systems receives even a middling score. Yet the overall rating is full black. This happens when no one area is notably troublesome, but there are enough extra issues across all problem areas to make the overall score “much worse than average.” This is consistent with our data, where there is no clear common problem with the regular Golf that might explain why its score is so much worse than the GTI’s.

One possibility: the GTI launched before the regular Golf, and it’s possible that quality checks were more thorough for the early cars. The line was almost certainly running more slowly at the beginning. No repairs were reported for the GTI in calendar year 2014. But two-thirds of the GTIs in the current sample were enrolled during 2015, and while the reported repair frequency is no longer zero it hasn’t shot up dramatically, only from 13 with the May update (covering through the end of the first quarter) to 17 with the August update and about 22 with the upcoming update. It’s still far below the mid-50s.

I’ll continue to pay extra attention to the Golf. For now this must remain an unsolved mystery.