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

Mercedes-Benz produce both gasoline and diesel versions of their current generation hybrids. The diesel hybrids are known for having a long highway cruising range, with the benefit of lower emissions in the city. The reason diesel hybrids are not more common is simply price – most people will opt for the cheaper gasoline version. In Germany people tend to opt for the diesel version only if they spend a lot of time on the highway and want to reduce refuelling stops.

Other manufacturers used to produce diesel hybrids up until a few years ago: Range Rover, Volvo, Peugeot. They were not very popular, so they were discontinued.

Edit for some more context: diesel engines are really good at running efficiently for long periods of time. The higher energy capacity of diesel allows for longer stroke, which means the engine can make good torque at lower speeds. This means there is less wear on the engine, which gives diesels their reputation for longevity. So a diesel hybrid is an attractive option if you are constantly running the engine, i.e. on long highway drives.

Petrol engines on the other hand are less efficient over time, but they are more suited to stop-start applications i.e. driving around town. Hybrids are also most efficient at low speeds around town, which is why they’re generally more suited to petrol engines.