2024 Lexus TX Has Three Powertrain Options – ICE, Hybrid, PHEV – and It Shows
Lexus used specific powertrain-transmission pairings to hit Lexus Driving Signature targets in the first-ever TX.
Despite its considerable size, the new Lexus TX does not lumber. It does not struggle. Instead, Lexus’ latest three-row SUV provides surprisingly smooth and relaxed acceleration along with an unexpectedly easy drivability for a vehicle this large.
The brand-new TX was developed intentionally for U.S. families to provide them with plenty of room – 20.2 cu. ft. with all seats up, 57.4 cu. ft. with the third-row seats down and 97 cu. ft. with all rear seats down – the ability to tow up to 5,000 lb. (2268 kg) and an enjoyable ride, according to TX chief engineer Naohisa Hatta.
“To achieve the dynamic performance that Lexus demands as a brand, the structural rigidity of the body is crucial. It’s essential,” Hatta told SAE Media. “We wanted to make sure it got a really strong foundation, along with high-rigidity suspension components. Steering was also a key, crucial area. If you don’t do that, there’s only so much you can do with tuning afterward.”
Feeling the power of the PHEV
SAE Media spent a day in Austin, Texas, testing all three powertrains in the TX. The plug-in hybrid variant, the 550h+, proved to have the smoothest power and acceleration, which comes from a 3.5-L V6 and a continuously variable transmission (CVT). The TX’s other models both use a 2.4-L 4-cylinder with conventional automatic transmissions, a 6-speed for the 500h hybrid and an 8-speed for the TX 350 base model. Compared to either hybrid, the TX 350 felt sluggish, but that’s just the inherent downside of relying solely on an ICE.
The 500h powertrain is exclusively available with the F-Sport trim. Hatta said the team felt that the 2.4-L turbo powertrain had ample power and torque to propel the vehicle even with six or seven occupants, but it wouldn’t be enough of a luxury feel for the upper trims. The F Sport trims also are the only TX versions with rear-wheel steering, which tightens the turning radius from 19 feet to 18 feet (5.8 m to 5.5 m).
“The F Sport and the luxury have unique characteristic differences,” he said. “The six-speed hybrid system for the F Sport, by using gearshifts to go through, is a much more interactive and responsive driving experience. The plug-in [hybrid], with the V6, uses the traditional CVT, so it has a much more linear feel with a very good response as well. The transmissions are all contributing to that target driving feel that we were aiming for.
Even though his team engineered the shift changes in the hybrid TX to feel more “interactive and responsive,” Hatta said the engineers decided to balance the acceleration feel with help from the electric motor.
“In a traditional transmission, as you upshift, the torque curve is going to decrease,” he said. “Because it’s a hybrid system, we use the motor assist to make sure that we can connect the dots of the torque curve as much as possible, so you don’t have that drop, the zigzag characteristic.”
Keeping some of the shifting noticeable was meant to give the driver a sort of “dialogue” with the vehicle, Hatta said, but this was tempered by the desire to fill in some of the drops with motor assist – but only up to a point.
“If we then go through and try to fill in all the [drops], then we’re going back to something where you don’t feel anything at all,” he said. “Then, it’s a tuning issue, a flavor issue.”
The TX is longer and wider than the Lexus RX and NX, but all three models share Toyota’s GA-K platform. The GA-K is the large-vehicle version of the Toyota New Global Architecture (TNGA) program. Hatta said all three vehicles started development at the same time, but the NX came out two years ago and the RX last year. Seeing how the RX and NX felt on the GA-K platform allowed his team to better refine how the TX drives.
“The TX had the longest development time,” Hatta said. “The structural rigidity enhancements that the NX incorporated, and those the RX implemented one year later. … We watched the NX and the RX, and then we learned from that, and we were able to apply even more efficiency to our application.
The 2024 Lexus TX starts at $55,050 and is built at Toyota Motor Manufacturing, Indiana. The TX is the first Lexus vehicle to be assembled there; the TX 350 and TX 500h trims currently are available, with the 550h+ going on sale in early 2024.