I’m confused too because imo the gas would ignite before diesel would. If they use, however, hot and compressed diesel gas, then the diffusion of the gas throughout the mixture would make an efficient and complete clean burn as opposed to a localized burn to spread from a single spark point.
Auto ignition temperature of natural gas is about twice that of diesel. The diesel is used to light off the NG. That idea has been around for many years.
Perhaps the increases in (thermal, I suppose)efficiency are coming from an elevated compression ratio, and perhaps staged injection to control cylinder pressures.
Seems like an answer to gov’t mandated lower emissions and utilization of a plentiful fuel as the means.
To liberals though, plentiful is bad, as that means lower cost, which means more consumption, and they want to control consumption. So costs will remain high, no matter what.