The brand’s most popular SUV model, the Lexus RX, has just been launched internationally with no plug-in hybrid option, at a time when almost every one of its competitors has such technology available.
Further, the Porsche Cayenne S E-Hybrid plug-in model is already here. And there are more affordable plug-in hybrid electric vehicle (PHEV) models such as the Mitsubishi Outlander PHEV, which starts below $50K.
The biggest benefit of a plug-in hybrid drivetrain is that it allows extra range on electric power only.
Currently, Toyota/Lexus’ hybrid models are able to cover only about two kilometres using battery power only, where rivals have up to 50km of claimed range.
Lexus RX chief engineer Takayuki Katsuda admitted that the current-generation RX model wasn’t designed to have plug-in technology as part of its packaging, due to a number of reasons.
“At this moment of time as you see, we are not ready for the PHEV for this generation RX. That is a fact. So we are going to launch without a plug-in hybrid.
“However the remarkable point is that from 10 years ago, already we introduced the so-called pure hybrid vehicle, and accumulation of such kind of gas mileage and the environmental benefit is already accumulated in the past 10 years,” he said.
“Also, the same way of thinking we are not following, because plug-in or upcoming technologies of course are very attractive and we need to challenge something.
“At this moment of time, even with the current pure hybrid system already we have good sales, and we are going to have also good sales scope for the future. That means when we calculate the benefit by the volume, it equals a good area. However total volume of the energy saving and the environmental improvement should be there.”
Katsuda said that despite broad-ranging incentives in markets such as Europe and the US that allow ownership of plug-in hybrid and electric vehicles to be more affordable, the costs involved are still high from the manufacturers’ point of view.
“The system itself is still rather expensive, and tax incentive is not so steady because of the times,” he said. “So far the most steady way to create a better future with low gas mileage and better emissions, we think, is still the pure hybrid.
“Mass volume is one of the solutions,” he said. “That is why at this moment in time we are going this direction.”
Katsuda said he believed that battery technology still has a long way to go, and that the weight and size of the current systems makes for difficulties in fitting bigger, bulkier packages to accommodate plug-in technology.
“There are quite complex issues still remaining,” he said, explaining that there are two options: changing to a new battery material, or making the current batteries more efficient.
“Changing something is also a good challenge, but our such kind of steady improvement result is also worthwhile for the better gas mileage.
“Even this original system launched 15 years ago, with the nickel type or the same motor, and improved motor of course, carried over – however, year by year, model by year, gas mileage and also the higher emissions [regulations] four, five and six – every step we can achieve.”
Katsuda admitted that plug-in models must be part of the broader solution in terms of better fuel efficiency and reduced emissions, but he said that other new technologies – namely hydrogen – also have a part to play.
“Yes, we already understand about the necessity of the plug-in. And this solution must be one of the solutions. But at the same time not only Lexus but corporate Toyota is now thinking about another solution, the fuel cell, for the [Toyota] Mirai.
“Therefore year by year, new ideas must come, we need to think every options at the same time, in the near future I think.
“From an engineer’s view point, of course we need to challenge every aspect of the new technology. Which technology will be mainstream of the future? At this moment of time it’s very difficult to see.”
Katsuda seemingly made it clear that if a PHEV model were to be developed and implemented by Lexus, it would need to make use of more high-tech batteries.
Currently Lexus is persisting with nickel metal hydride (Ni-MH) batteries, but there are models in the Toyota range with more advanced lithium battery cells. Ni-MH batteries are cheaper but less energy-dense, where lithium-ion batteries have better energy density and are claimed to have no memory effect.
“Yes, plug-in is a good option, but if in case of chasing the plug-in more, it’s my personal opinion, but if so, the more high-density technology must be necessary,” he said, suggesting lithium-ion batteries would be the key to that technology working in a Lexus.
“At the moment battery technology is limited, in case of having twice or three times more distance, then twice or three times more heavier the batteries have to be put in.
“Such kind of layout or packaging of the car can be possible, but the weight cannot be reduced.
“Otherwise in case of the accumulation of current lithium or other existing batteries, the total vehicle weight will be just simply increasing.
“Therefore, compared to the nickel-metal hydride to lithium, lithium is lighter. But even if you use, we need to have some certain amount of several hundred kilograms of batteries for extending the range [for] PHEV.
“The concept of the plug-in means having a huge sizes of the stocks of energy charging, so conceptually it’s very correct I think.
“But how to, or current going direction with PHEV with lithium is a final solution that I’m not sure [about] at this moment in time.
“At the moment we are satisfied about the current technology because again the pure hybrid has smaller battery sizes but the total package, the lightweight package and still the roominess has been kept in the current car. And also the pricing is still affordable, not dependent on the tax regulations.”