droopy is precisely correct on the technical comparison between a blockchain and tangle orientation in the case of HDAC and IOTA. I will play devil's advocate for a moment however, as I do not believe these projects will necessarily develop based on the technological considerations alone.

At the end of the day, all of these crypto-projects are going to require a serious infrastructural investment with commensurate merchant support implementation. In other words, the protocols can be perfectly sound and utilitarian, but if there is no point-of-sale mechanism in play, then it's all theoretical. Hyundai has the capital at its disposal to close this practical implementation gap exponentially quicker than IOTA. It stands to reason that since they will stand to gain the most in this venture, they will be very motivated to throw their considerable industrial/commercial weight behind promoting (pressuring) merchants and vendors to accept their system.