 2008 Chevrolet Tahoe Hybrid |
Mild Hybrid vs. Full Hybrid
GM isn't all that new to the hybrid market, but until now all of its hybrid vehicles like the Chevrolet Malibu Hybrid and Saturn Aura and Vue Green Line models have been categorized as "mild hybrids." These systems save gas with an automatic shut-off function during stops and electric assistance during ignition and launch, but don't allow for the operation of the vehicle in electric-only mode. Vehicles like the Toyota Prius and Ford Escape Hybrid operate as full hybrids and save more fuel by using the electric motor independent of the gas engine for lower speed, around-town driving.
Similarly, the new 2-Mode system features the above mild hybrid functions but also allows the vehicle to operate using solely the gas engine, solely the electric engine, or a combination of the two depending on the driving situation.
The 2-Mode system combines GM's 6.0-liter V8 engine and a 300-volt nickel-metal hydride battery powering two 60-kilowatt electric motors. Regenerative brakes capture the energy normally lost when slowing down and use it to recharge the battery. The engine and motors mate with a unique 4-speed automatic transmission that works like a continuously variable transmission in low-load and low-speed driving situations but also has four fixed gear ratios, like a standard 4-speed automatic transmission, for towing or highway driving.
The 2-Mode name refers to these two transmission modes used for the two types of driving situations (low-load, low-speed and high-load, high speed) and how the vehicle's gas engine, two electric motors, and transmission adjust to be the most fuel efficient in each situation.
In city driving, the vehicle is traveling at lower speeds and is constantly stopping and going. Here, Tahoe Hybrid starts off using just the electric motor and is able to run under electric-only power in light acceleration, low speed situations for several miles. This is where most of the fuel savings are recognized.
Tahoe Hybrid's 6.0-liter V8 features Active Fuel Management that allows for cylinder deactivation, which comes in handy for the second mode: higher-speed highway passing and towing. The vehicle is in full V8 mode during brisk highway acceleration, towing, and hill climbs, but can scale down to 4-cylinder mode with electric assist during higher-speed around-town driving or highway cruising.
Hybrid Inside and Out
While GM stressed the importance of Tahoe retaining its stout, utilitarian image, the Hybrid model does stand apart from other Tahoe models.
 2008 Chevrolet Tahoe Hybrid |
The Hybrid model's navigation screen features a helpful energy flow display that indicates what driving mode the vehicle is in; complete electric mode, gas V8 mode, or electric-assisted gas 4-cylinder mode. Likewise, the efficiency gauge in the upper left corner of the instrument panel indicates the most efficient braking range to capture regenerative braking energy.
Fuel-Economy Challenge
I put GM's Camry claim to the test during a recent drive through the city streets of San Diego, California. According to the trip computer, the end fuel economy result during my test of a 2WD Tahoe Hybrid was an impressive 22.9 miles per gallon over nearly 50 miles of 100 percent city driving. However, my eyes were glued to the efficiency gauge and energy flow display during the test, so I was constantly aware of my fuel consumption and did everything I could to drive efficiently.
However, even heavy-footed drivers will see considerable fuel savings compared to other vehicles in this thirsty class. On a recent highway and around-town drive, one CG editor averaged approximately 18 mpg during a 150-plus mile drive. The EPA estimates a 2WD Tahoe Hybrid averages 21/22 city/highway miles per gallon, and a 4WD model 20/20 city/highway mpg.
This fuel savings, however, comes at a steep price. Two-wheel-drive Hybrid models start at $49,450 but come equipped with the larger engine and convenience extras like a rear-obstacle-detection system with rearview camera, tri-zone automatic climate controls, leather upholstery, heated six-way power front bucket seats, third-row three-passenger split folding seat, navigation system, and remote start--to name a few. The 4WD model adds 4WD to that for a $52,395 base price.
So while Tahoe Hybrid will save you money at the pump, it will also sharply increase your bottom line at the dealership. Then again, this full-size SUV has the ability to get the fuel economy of a midsize car without sacrificing much towing capability or cargo and passenger capacity. It also leaves less of a negative impact on the environment. What's that worth to you?
