It seems to be a mixed bag. https://www.iaati.org/news/entry/thatcham-releases-latest-results-of-motion-sensors-in-key-fobs-that-block-r https://www.iaati.org/n

It seems to be a mixed bag. https://www.iaati.org/news/entry/thatcham-releases-latest-results-of-motion-sensors-in-key-fobs-that-block-r https://www.iaati.org/news/entry/thatcham-releases-latest-re... I guess sleep mode is really more about preventing relay attacks, with improved battery life being a side effect.