Hacker News Reader

They might be referring to the Atkinson cycle engine, which is really just adjusting the valve timing. Lower power but higher efficiency.

https://www.autoweek.com/news/green-cars/a1832081/atkinson-c...

View on HN

No, it means that you can leverage a more efficient part of an engine’s torque curve by supplementing with electric power at the low and high end (since motors have a flatter torque curve).

Not just that. It does require Atkinson cycle to reach the efficiencies they have. It just means that the compression stroke is shorter than the power stroke.

Basically with that cycle they can get massive compression ratios. As an example newer Toyotas are at 14:1 ratio with 41% thermal efficiency. That’s close to diesel territory on a gasoline car.

Naturally when you floor it it goes to Otto cycle and efficiency drops.

And, in the case of Toyotas eCVTs, keeping the ICE in the most-efficient-rpm sweet spot longer by allowing the ICE RPM to be pretty much independent of the wheel RPM. It's somewhat strange because RPM noise barely correlats with speed or acceleration anymore.

Also: start-stop-automatic for free ... I am still somewhat spooked when the motor just turns off going 70 km/h because the ECU decides that the ICE is not needed anymore.

Reply on news.ycombinator.com