The federal reserve excludes food and energy because they are more noisy and don't want to be hiking interest rates based on random fluctuations that won't last. The way shelter is incorporated into CPI is well known to be bad. They were saying a year ago that it would lead to higher CPI numbers for a long time after inflation stopped. Excluding used cars seems like pure cherry picking: this number sucks too much so we will not look at it.

They don't want prices to come down or even stop going up. They want them to stop going up too fast.

Krugman is an idiot, mainstream economics is a pseudoscience, inflation seems to be still too high. Just trying to explain what he thinks he's doing.