Probably one of the main reasons for a consumer to consider the Mercury Mariner Hybrid is clearly the promise of excellent fuel economy for a compact SUV. The hybrid powertrain delivers a driving experience very much like a traditional gasoline only powered car. The hybrid architecture for the Mariner is very much like that of the Prius. The differences are mostly limited to the size of the gasoline engine capacity, the power of the electric motor, and the battery pack size. To take full advantage of the high torque of the electric motor, the Mariner uses an Atkinson cycle engine, which offers high efficiency at the expense of low-end torque. This Atkinson cycle engine opens the intake valve late to reduce engine pumping losses. This results in a relatively low compression ratio, but a high expansion ratio during the power stroke. This combination of a highly efficient gasoline engine with the hybrid components promises an estimated EPA fuel economy of 29 mpg and 32 mpg highway and city respectively. The question on everyone's mind is clearly if the Mariner Hybrid delivers the promised fuel economy.

Read more after the jump to see our results.
During the first day of mixed highway and city driving conditions, the Mariner Hybrid delivered an average fuel economy of about 27.6 mpg, more than 10% below the EPA estimated numbers. While still offering a significant improvement over the 4cylinder and 6-cylinder Mariners, making up for the higher purchase price would take quite a long while. On the second day of the Mariner test, however, I reset my average fuel economy up to that point and decided to keep the LCD readout on the instant fuel economy readout. From day two on, I tried to adjust my driving style to improve fuel economy. Slowly but surely, the average fuel economy inched up. Restrained acceleration, sticking to the speed limit a little more closely, and keeping the speed below 20 mph or so when going from stop sign to stop sign increased the average fuel economy to 31.4 mpg over about 500 miles of driving, 300 of which were freeway miles. While adjusting your driving style is a proven way to improve fuel economy in a traditional gasoline engine, it seems to be even more important when driving a hybrid, something to keep in mind if you are in the market for a hybrid.





So how does the Mariner Hybrid stack up when compared to its competition? The only other currently available hybrid SUVs - the Toyota Highlander and Lexus RX 400h - offer comparable EPA estimated fuel economy, but are priced higher and are larger. In addition, their real-world fuel economy has been reported to be more around 25 mpg, which seems to be expected since they are both heavier vehicles with larger gasoline engines and smaller battery packs. The Mariner Hybrid and its close cousin the Ford Escape Hybrid can, without hesitation, be called the most fuel efficient SUVs currently available on the market. For those consumers looking for a fuel-efficient vehicle with the space offered by a compact SUV, the Mercury Mariner Hybrid offers an excellent choice (especially if you prefer a more stylish alternative to the Ford Escape). The Mariner is lacking some features available on the competition, but that might be a sacrifice many of you are willing to make, in light of rising fuel prices. Hurry up, only 2000 will be available for 2006.



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