What’s that, you say? You’re looking for an engine that can vary compression? In a super high-tech Infiniti SUV concept? Then look no further than the Infiniti QX50 Concept.

Infiniti says that the concept will have new “autonomous drive support technologies”, which will act as a “co-pilot” to the driver, instead of replacing him or her completely. Which, at this point in time, sounds like super-duper fancy cruise control to me, par for the course on new cars these days. Boring.

But! Under the hood is where the party is. Infiniti’s new engine is a 2.0-liter turbocharged gasoline engine that can vary its compression. This way, the engine can deliver both the performance of a high-powered 2.0-liter gas engine and the torque and efficiency of a diesel engine.

Infiniti showed off a slightly updated Q50 yesterday at the Paris Motor Show, but nobody gave a…

Here’s how it works, according to our own David Tracy:

Basically, there’s an electric motor that rotates a cam, which pushes an actuator arm, spinning a “control shaft.” There’s a lower link attached to that control shaft, which gets pushed and pulled when that shaft is spun (presumably because the lower link and the control shaft have off-set axes, just like throws on a connecting rod).

That pushed (or pulled) lower link yanks shoves the multi-link, which rotates about the crankshaft, pulling or pushing the upper-link to change how high the piston goes in the cylinder, thus altering the compression ratio. The piston goes higher in the cylinder (high compression) when the driver is light on the gas, and it’s lower (for lower compression) when the driver is deep on the pedal to reduce the risk of pre-ignition.

There is some extremely cool stuff at work here. We’ll be able to get a closer look at both the car and the engine at the Detroit Auto Show next week.