We recently had the opportunity to drive the new Lexus RX 400h luxury hybrid throughout the Kohala Coast on the big island of Hawaii. This vehicle is based on the Lexus RX 330, but make no mistake, they're two very different animals. The all-wheel-drive 400h was designed to integrate luxury, performance, improved fuel efficiency and reduced emissions. It definitely highlights state-of-the-art hybrid technology.
Interestingly, the 400h is equipped with one ICE and three motor/generators. Its ICE propulsion system is a 3.3L V-6 engine that produces 208 hp and 212 lb-ft of torque. This engine is mated to a motor/generator (called MG2) that drives the front wheels and offers regenerative braking. It has a maximum output of 167 hp and 247 lb-ft of torque. Instead of a familiar rear axle and driveshaft, the 400h has a rear-mounted motor/generator (called MGR) that can create 68 hp and 96 lb-ft of torque, but drives the rear axle through a speed reducer that allows it to provide up to 650 lb-ft of axle torque. This motor/generator drives the rear wheels and offers regenerative braking. Additionally, a third electric motor/generator (called MG1) generates power, acts as a starter motor for the engine and controls the transmission ratio. Electrical current for the motors comes from a nickel-metal hydride battery pack that has a nominal voltage of 288 volts and a power output of 45 kW.
Driving the 400h is, on the one hand, surprisingly uneventful because of the seamless nature of the powertrain. The power just happens. On the other hand, it's an event unto itself, due to the vehicle's impressive horsepower and torque, finely tuned handling, luxurious appointments and impressive fuel economy. Lexus says the 400h can scoot from zero to 60 mph in about 7.3 seconds and accelerate from 30 to 50 mph in a respectable 3.4 seconds, all the while getting an EPA-estimated 30 mpg in the city. That's quite impressive for a 4,365-pound SUV. Since Lexus asked us to please refrain from deviating from the drive route to trail-test the 400h, we had to settle for some dirt parking lots to test the AWD system. Once again, seamless is the word, as the computer electronically varied the front and rear torque distribution to compensate for traction conditions. It was weird to think that a 90-pound electric motor was the sum total of the actual rear drive system and that it could produce so much torque.
Dodge is working on a diesel hybrid-a technology being pursued by DaimlerChrysler-that's based on the Ram Heavy Duty chassis. It will be equipped with the company's 325hp/600lb-ft Cummins diesel engine. Dodge says the truck will generate a real-world fuel economy improvement of approximately 15 percent over a comparable non-hybrid diesel-powered Ram Heavy Duty. Like the Silverado Hybrid, the Dodge Ram HEV will offer electric generator capabilities. It will provide enough 110/220-volt AC electricity to power four average U.S. households.
The hybrids of today are technological marvels, but the concept of hybrids began back in the late 1890s. The most important of them debuted at the Paris World's Fair in 1900, and was the Lohner-Porsche, built by Dr. Ferdinand Porsche and Jacob Lohner. It used an internal combustion engine to spin a generator that provided power to electric motors located in the wheel hubs. It's said that on battery power alone, the car could travel nearly 40 miles before needing a charge. About 800 of them were said to have been built.
In 1910 the Commercial Company built a hybrid truck, which used a four-cylinder gas engine to power a generator, eliminating the need for the transmission and battery pack. Completely electric cars were on a roll during this period because gasoline cars were noisy, smelly and, most importantly, difficult to start. However, electric and hybrid vehicle sales hit the skids in 1913 following invention by Clyde Coleman and Charles Kettering of the electric self-starter for internal-combustion engines. This was first installed on a Cadillac in 1911. Following that, sales of electric cars dwindled, but Ford Model T sales sharply increased thanks to the new invention.
It wasn't until 1997 that the first production hybrid was released by an automotive manufacturer. It was the Toyota Prius and it first went on sale in Japan. Three years later the Prius was introduced in the United States.
Unlike an internal-combustion engine, an electric motor has the ability to reverse. This reversibility allows the same motor that runs on electricity to reverse and use torque to generate electricity that can be used to charge the hybrid system's batteries. This would be like rolling your truck backwards and having the engine generate gasoline. Wouldn't that be cool? Exactly when regenerative braking occurs depends on the specific hybrid system, but the computer in most full hybrids tells the electric motor to switch to the electric generator when you lift your foot from the accelerator. As you decelerate, the wheels turn the electric generator (formerly the electric motor). This does cause drag in the driveline, which you can feel, but you still must use standard friction brakes to decelerate completely.