IIRC, that it's the same engine, just turned up higher, some ratings have different turbochargers, others do not.
The new X12 engine is more fuel efficient and up to 600lb lighter than some of it's competitors. That's more income per mile, which is what it's all about. More cargo, less fuel.
Torque is a two edged sword. Big torque limits your transmission and axle choices, and raises the empty weight because of that, and reduces overhaul hours. When torque gets really huge, they rely on hybrid powertrains like you see in locomotives and earth movers. However large displacement diesels have the best BSFC (economy) because of their high torque. High torque is simply high horsepower at lower RPMs. Low RPMs allow less frictional losses, more complete burns, and higher chamber pressures.
You can make an EV Class 8 with more HP and TQ than a conventional drive. Can you make it generate more $ per mile is the question.
Hence why I'd aim at the medium duty / bus / RV market. With those apps, it's not alway $ per mile. Sometimes governments want the EV for political reasons, buses clean the inter-city air quality, and RV's are often judged by how trick they are as opposed to economy.
