We have already carried out a detailed analysis on diesel and non-plug-in hybrid cars. We have wondered what would happen if car brands decided to combine diesel and electrons.
And if electric motors are very efficient when it comes to transmitting power to the wheels and, on the other hand, no other fossil fuel provides more km per liter than diesel… Why is there so little commitment to cars? diesel hybrids? We tell you in detail in this video:
Problems with diesel hybrids
When choosing to hybridize a car, gasoline is mostly chosen, there are several “original” sins of diesel hybrid technology
- Complexity: A diesel engine is excellent at low revs… just where the electric engine is ideal, which cannot complement it as well as a gasoline engine. This ends up complicating electronic management, to avoid sending excess torque to the gearbox.
- Startups: Hybrids are fabulous in the city because of their smooth operation during continuous stops. That's exactly when a diesel is most noticeable, when you start it. No matter how good and refined it is, the vibrations are noticeable due to its higher compression ratio. In addition, a gasoline works better at lower temperatures.
- Weight: A diesel block weighs more, if you add the electric motor, batteries and other auxiliary systems, you lose efficiency. They are also more voluminous, you need bigger cars.
- Reliability: Gasoline hybrids stand out in reliability, but a diesel needs turbo and direct injection, in addition to other delicate systems to control gases such as the EGR valve, particulate filter or Adblue.
A minority of manufacturers currently combine diesel blocks with diesel engines. Regardless of whether they are plug-in or not, there are very few diesel hybrids on the market. We usually distinguish three types of hybrids and depending on them there are more or fewer options:
Mild hybrid diesel
These hybrid systems are the simplest. Have ECO labelbut they cannot move the car exclusively with electric power even a few meters.
The largest offer comes from premium German manufacturers. From midsize sedans to premium SUVs. We are talking, of course, about Audi, BMW and Mercedes, which have not hesitated to add 48 volt systems to their diesels to obtain the ECO label on the largest models in their ranges.
- Audi: Audi A4, Audi A5, Audi Q5, Audi A6, Audi A7 Sportback, Audi Q7, Audi A8.
- bmw: BMW 3 Series, BMW 4 Series, 5 Series, X3, X4, 6 Series, X5, X6, X7, 7 Series, 8 Series.
- Mercedes: C Class, E Class, GLC, CLE, GLE, GLS
The same goes for Jaguar Land Rover. Mild hybrid diesel can be found in many models from these manufacturers, especially in the SUV range with more of an off-road focus.
- Jaguar: Jaguar XE, E-Pace, Jaguar XF, F-Pace
- land rover: Discovery, Discovery Sport, Defender, Range Rover Evoque, Range RoverVelar, Range Rover Sport, Range Rover
Volvo manufactured its last car with a diesel engine on March 26, 2024. If you want a diesel hybrid from the brand, you have to go to the second-hand market. Mazda mounts it on the Mazda CX-60 only. And among generalists only hyundai kia They bet on them, in models such as the Tucson, the Sportage and the Ceed range.
- Mazda: Mazda CX-60
- hyundai: Tucson
- kia: Ceed, Ceed Tourer, Xceed, Sportage
This means that you can find a light gasoline hybrid from around 13,500 euros (the Panda 1.0 Hybrid) and you have to spend almost double that to find a light diesel hybrid, €27,200 for the Kia Ceed Concept 1.6 CRDI MHEV.
So little supply, from only eight manufacturers and also focused on expensive models, has meant that mild hybrid diesels sold six times less in Spain than gasoline ones in 2023. At the start of 2024 the difference is even greater. For every diesel hybrid, eight gasoline hybrids are sold.
| YEAR | HEV gasoline | diesel HEV |
| 2018 | 74,555 | 1,218 |
| 2019 | 94,141 | 14,543 |
| 2020 | 112,775 | 24,650 |
| 2021 | 182,243 | 37,180 |
| 2022 | 208,481 | 34,987 |
| 2023 | 264,104 | 43,720 |
| Q1 2024 | 79,171 | 9,812 |
Conventional diesel hybrids. ECO label.
There are no full hybrid diesels (conventional hybrids) on the current market. It was tried and this innovation came from France, specifically from PSA. We met it in the Peugeot 3008 Hybrid4 in 2012, but it was later mounted in the Peugeot 508 RXH and also came to the DS5 Hybrid4.
They combined a 163 HP 2.0 HDI four-cylinder diesel engine that moved the front wheels with a 37 HP electric engine that was responsible for moving the rear wheels up to 120 km/h. In total, 200 HP of power and all-wheel drive… as long as you went at a lower speed.
They could operate only with the electric motor up to 70 km/h, becoming a propulsion car. The idea did not catch on because it was an expensive system and the consumption did not differ too much from a conventional diesel.
Despite this, the brand continued to explore how far this technology could go with the Peugeot Onyx Concept.a spectacular prototype that combined a 3,700 cc HDI V8 with an 80 HP electric motor to achieve 600 HP.
The kings of diesel are the Germans and they also launched proposals at the time. We remember the engines Mercedes BlueTec Hybrid. In the C, E and S Class, they combined four-cylinder diesel blocks with a 27 HP electric motor and were smooth and very comfortable, as we saw in the E 300 BlueTec test.
BMW did not launch any diesel hybrids on the market, but Audi came close to doing so. Logical, when seeing the Audi R18 e-tron Quattro. It had a 3.7 TDI engine and 510 HP, with a hybrid system and all-wheel drive. He won Le-Mans in 2012, 2013 and 2014 and that led him to present the RS5 TDI Concept at the end of 2014 with a 385 HP diesel V6 and a lithium-ion battery that allowed energy to be recovered.
What killed the possibility of the first diesel RS in history? Well, the Dieselgate scandal of 2015. From then on, diesel began to disappear from the market in leaps and bounds.
Diesel plug-in hybrids. Label Zero
Only Mercedes. You can recognize them by the name (electric diesel). But before that there were some attempts. Coincidentally, they came from the Volkswagen Group. The first step was taken by Audi, which had to demonstrate that they were at the forefront of technology.
After two Audi Duo prototypes, based on the Audi 100 platform, the Audi Duo TDI appeared in 1997. It had on the one hand the well-known 90 HP 1.9 TDI and on the other a 29 HP electric motor. Based on the A4 platform, only 60 units were sold. Then came, in 2014, a diesel plug-in hybrid like no other, the Volkswagen XL1.
It was quite an engineering challenge proposed by Ferdinand Piech, to consume 1 l/100 km. They achieved this thanks to extraordinary aerodynamics and a weight of just 800 kg. Only 250 units were manufactured, which cost like a sports car, more than 100,000 euros… and Volkswagen lost money with each unit sold.
Audi returned to the fray with the Q7 e-tron…and Volvo also tried it with the V60 Plug-In Hybrid with an idea similar to that of PSA, but plug-in… but Dieselgate demonized diesel not only in the VW Group. Diesel's bad reputation spread throughout the passenger car world, and tightening emissions standards didn't help either.
And despite everything, Mercedes opted for this technology. There is a reason: they developed it before diesels fell out of favor and decided to go ahead to amortize the investment. In the variant 300 of: Combines the 2.0-liter four-cylinder diesel engine with 197 HP that you can find in the Mercedes GLC 220 d. On the other hand, an electric motor with 136 HP. In total, 333 HP of power and 750 Nm of torque. The best thing to know if you are interested is to read our in-depth test of the Mercedes GLC 300 Coupé.
