Amid all the hot cars at the Paris Motor Show, Infiniti has introduced a breakthrough new engine

The Paris motor show doesn't lack for sexy cars and exciting new concepts. But while all that's been going on, Infiniti revealed a breakthrough new engine technology.

It's called the VC-Turbo, and it's important.The world is very busy these days thinking about an electric-car future, but the vast majority of the vehicles on the world's road are powered by internal combustion engines and will be for decades.

And before you start thinking that IC engines are yesterday's dirty tech, don't forget that automakers have been continuously innovating with them for a century.

The new VC-Turbo is a great example. In a statement, Infiniti said that the 2.0-liter four-cylinder powerplant "promises to be one of the most advanced internal-combustion engines ever created."

The VC stands for "variable compression," and it means that the new motor can modulate its compression ratio to optimize its performance. According to Infiniti, it combines the torque of a diesel motor with a high-performance gas engine - minus the emissions problems that small-displacement diesels confront.

The VC-Turbo is to engines what a continuously variable transmission (CVT) is to shifting gears: it can locate the ideal compression ratio for a given driving condition. Infiniti has been working on the technology for 20 years and thinks it will enable the automaker to offer better performance with a four-cylinder motor, replacing six-cylinder powerplants.

The VC-Turbo will go under the hoods of Infiniti vehicles in 2018.