Combine that instant torque with the electronically controlled continuously variable transmission coupled to the V-6, and you get seamless, inexorable acceleration that doesn't necessarily push you into your seat, but it does destroy any vestigial associations between "hybrid" and "golf cart." Weaving through traffic was a breeze, not the hurricane of a supercharger or gale of a high-displacement mill, but the torque was always available to zip around some 60-mph slowpoke. We did make the tires chirp by mashing the pedal while turning corners, and the Highlander Hybrid did beat our borrowed Honda Ridgeline off the line in an impromptu test of both vehicles' holeshot. Toyota claims a 0-60 of 7.3 seconds for this model.
The Highlander Hybrid's acceleration made scooting through the mountains kind of fun. The vehicle was stable going around the curves, although we wouldn't call the suspension performance-tuned. We noticed the hybrid system's battery got sucked almost dry very quickly during the uphill leg, necessitating an increased reliance on the gas engine. Driving downhill was facilitated by sliding the shifter to B, which provided the "engine braking" that you don't get anymore from the Hybrid version of the Highlander, and the gas engine hardly turned on at all. Fuel economy through our 105-mile trek through the mountains was 21.5 mpg, barely lower than the 22.85 mpg we got from combined street and highway driving.
3 Hybrid SystemsThere are three different kinds of hybrid powertrains out there: series, parallel, and series/parallel.
Series Hybrid: What you have here are three motors running in series. An internal combustion engine drives an electrical generator, which, in turn, powers an electric motor that ultimately spins the vehicle's wheels. One of the hallmarks of this approach is that the internal combustion engine can run at a constant, optimal rpm while it turns the generator, allowing the engine to run efficiently and durably. Series hybrids don't necessarily require a mechanical transmission, either, since the electric motor doesn't need gears to stay in its optimal powerband. Diesel train engines use this sort of arrangement; the diesel motor powers the system, while the electric motors do the actual work.
Parallel Hybrid: Both the internal combustion engine and the electric motor drive the wheels of the vehicle. There is one electric motor. And since generators and motors are basically structured the same way, the motor does the double duty of driving the wheels and charging the batteries. The drawback is that the electric motor can't do both of these jobs at the same time, which is why a parallel hybrid can't power the wheels with electric power alone and charge the battery at the same time, but it can rely on just the internal combustion engine to propel the vehicle.
Series/Parallel Hybrid: This combines the attributes of both approaches. Comprised of an internal combustion engine and two electric motors, the system can propel the vehicle with the engine only, electric motor only, and with both, and charge the battery at the same time. Software decides what the most efficient propulsive mix is needed for the conditions at hand. The Ford Escape Hybrid (and its cousin, the Mercury Mariner Hybrid) and the Toyota Highlander Hybrid are examples of this.