I saw a video once of a SAAB variable compression engine, it was being translated to me by a Swedish guy, in between the video they spoke of using this technology to lower diesel compression ratio.

What they meant was that the engine would do to a high ratio 22:1 to start and would change to about 16:1 to run.

It had a connecting rod type setup to tilt the block away from the cylinders.

I think that Mazda must have been using their history books for this - their miller cycle engine was also a strange design that played around with compression (not static)

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)