Hybrid vehicles have become in fact standard and are increasingly sought after on the market, either with mild or plug-in hybrid drives. But buyers of more upmarket Toyota and Lexus models are increasingly demanding performance that goes beyond mere fuel economy – their focus is shifting to driving feel, stability and on-road reliability. A possible answer to these customer demands can be seen in a new patent filed by Toyota in June 2025, which was published by the US Patent Office earlier this year.
Optimization of the vehicle’s center of gravity
Titled “Hybrid Electric Vehicle,” the patent does not describe new motors or batteries, but instead focuses on a radically altered arrangement of existing components. According to the documentation, the internal combustion engine remains located at the front, while the drive shaft connects the front to the rear axle assembly. This assembly combines the electric motor, transmission and differential, which, it seems, will be especially important for rear-wheel drive vehicles.
The key change is described precisely in the rear part of the car. Instead of the traditional position, the fuel tank has been moved forward, closer to the center of the vehicle, while the battery is positioned above the rear transmission assembly. Such an arrangement should allow the weight of the fuel, which decreases during driving, to change closer to the vehicle’s center of gravity, so that the steering remains predictable and stable. On the other hand, the battery, whose mass is constant, ensures constant pressure on the rear (drive) axle, which improves traction.
Balance and safety
In addition to the dynamic advantages, Toyota also emphasizes an important safety component – in the event of a rear-end collision, the battery is the first to absorb the impact, which additionally protects the fuel tank and reduces the risk of the fuel supply system catching fire (they don’t seem to worry too much about the battery catching fire in this case).
The technical details of the patent also reveal a complex heat management system. The hybrid vehicle includes a piped cooling circuit that regulates the temperature of the rear transmission. Special attention was paid to the location of the exhaust pipes that extend from the engine, located in front of the passenger cabin, all the way to the rear of the vehicle, passing laterally along the key components of the drive.
The cooling system is strategically placed behind the driver’s and passenger’s seats, and the coolant pipes are located above the exhaust pipes. Such a configuration, together with the precise placement of electronic control units and batteries, serves not only to maintain thermal balance, but also to additionally balance the total mass of the car.