According to Toyota, mild hybrids are not true hybrids
For many decades, choosing the right engine when buying a car was incredibly simple. You chose either a gasoline or a diesel engine—that was basically it. Over the past 20 years, the whole process has become significantly more complicated with increasing technological diversity and stricter emissions regulations.
Buyers today are bombarded with abbreviations: MHEV, HEV, PHEV, EV/BEV, REEV, and FCEV. If you're a car enthusiast, you probably know what they mean. But a "John Doe" doesn't live and breathe cars like you or we do.
This multitude of hybrid systems is causing a lot of confusion—and the world's largest automaker wants to make sure no one feels misled. Sean Hanley, Vice President of Sales and Marketing at Toyota Australia, told Drive magazine that Toyota does not consider vehicles with mild hybrid technology (MHEV) to be true hybrids.
"In our opinion, a 48-volt assist system is not a hybrid drive. We don't count 48-volt systems as HEVs [Hybrid Electric Vehicles]—just to be clear. They're not hybrids, not even close. That's why we want to clearly differentiate these three technologies."
The Toyota manager believes that manufacturers have a responsibility to use the terms clearly so that customers know what they are actually buying: "I think the OEMs (Original Equipment Manufacturers) have a duty to provide clarity here."
Ironically, Toyota itself markets cars with 48-volt technology as "hybrids" in some markets. In Europe, for example, the Land Cruiser Hybrid 48V and the Hilux Hybrid 48V were introduced a few months ago. Both models—SUV and pickup—are described as vehicles with an "electrified powertrain." Instead of a conventional generator, they use an electric motor-generator.
What is a mild hybrid anyway?
In a mild hybrid, the combustion engine drives the motor-generator, which in turn charges a small lithium-ion battery. A DC-DC converter regulates the energy flow between the battery and the motor. This system ensures a smoother and quieter start-stop behavior, but generally cannot power the car electrically alone.
So why do mild hybrids even exist? It's quite simple: On paper, they offer slight fuel consumption advantages at minimal cost and little additional weight. A 48-volt system obviously doesn't achieve the efficiency of a true hybrid (HEV) or even a plug-in hybrid (PHEV). But given increasingly stringent CO2 regulations, they are an affordable way to reduce emissions somewhat. In the Hilux, for example, fuel consumption and CO2 emissions are reduced by around five percent.
Advantages of a mild hybrid
According to Toyota, mild hybrids accelerate more smoothly from a standstill and decelerate more smoothly than cars with a pure combustion engine. Furthermore, less energy is lost because the system regenerates energy when the accelerator is lifted—recovering energy that would otherwise be wasted. This stored energy is then used to operate the start-stop system and assist with starting.
Toyota now covers the entire spectrum—from mild, full, and plug-in hybrids to pure electric vehicles (BEV/EV) with batteries or fuel cells (FCEV). And the company is already working on a new generation of gasoline engines that are intended to be suitable "for every type of application," as Andrea Carlucci, Vice President of Product Strategy & Marketing at Toyota Europe, recently explained. What this means is that these new engines could also serve as generators in electric vehicles with range extenders (REEVs) in the future—which would allow Toyota to cover almost every conceivable drive system.