Why are all modern hybrid and plug in hybrid cars paired with gas engines rather than diesel engines? The diesel and hybrid pair seem like a great idea in theory.

Question

A lot of people see hybrids and plug in hybrids as a great middle ground between ICE and EV, so why not make a diesel hybrid. They can be used in a variety of vehicles, and can reduce the nox and particulate emissions diesels are known for. So why isn’t there a modern diesel hybrid being produced, at least as a passenger car?

In: Engineering

Answer 1

Because in order to eliminate those particulate diesel emissions you need a lot of pretty expensive gear and a hybrid engine by its nature is also very expensive.

So most civilian consumers won’t be willing to buy what becomes a very expensive car for marginal savings in fuel economy between diesel and petrol.

The torque VS speed profiles of diesel, petrol and electric engines also show that diesel-electric hybrids are somewhat suboptimal.

Diesel engines excel at sustained medium speeds so work best on long distance endurance travel, while electric engines are best with low speeds and frequent accelerations/deceleration so inner city travel.

The two profiles conflict whereas petrol engines work best at high speeds like that on highways.

However diesel-electric engines do have a place in moving big and heavy things around like train locomotives, some tanks, ships and submarines all of which frequently use diesel-electric engines.