|Nissan Skyline 250GT.|
A Nissan driving team extracted 38 mpg from a new conventional 2.5-liter Nissan Skyline in an “eco-driving” challenge on real roads with unpredictable traffic and weather conditions and with different drivers.
The Skyline model, powered by the VQ25HR V6 engine (225 hp / 168 kW of power and 262 Nm / 194 lb-ft of torque) covered a 1,024.4 kilometer cross-country course with an average fuel consumption rate of 16.3 km/liter (38 mpg US or 6.1 l/100km).
Nissan began VQ engine production in 1994 and had produced a cumulative total of 5.5 million units as of last fiscal year, ended March 31, 2006. The new 2.5-liter VQ25HR engine and its larger cousin, the 3.5-liter VQ35HR, offer a 10% improvement in fuel efficiency compared to vehicles equipped with the prior generation of VQ.
The new VQ engines (the new HR suffix represents high rate of revolution and high accelerator response) feature a number of enhancements:
Reduction of weight and friction through adoption of asymmetrical piston skirt configuration. Nissan reduced the skirt width on the side with the least amount of pressure, resulting in reduced friction.
Minimizing piston inclination, thereby reducing friction, by lengthening the con rod;
Addition of rudder frame, newly-designed cylinder block with significantly improved rigidity;
Adoption of continuously variable valve timing control (CVTC) for intake side and electromagnetic valve timing control (e-VTC) for exhaust side;
Reduction of intake resistance through adoption of symmetrical twin intake system and straight intake port;
Reduction of cam-valve lifter friction by 40% through adoption of world’s first hydrogen-free, diamond-like carbon (DLC) coating; and
Adoption of catalyst substrate with ultra-low heat mass, super-ignition iridium spark plug and fast light-off O2 sensor control.
Overall, Nissan made more than 40 improvements to increase fuel efficiency by 10%.
The 1,000km drive took place on 16 March with a team of eight test-drivers under the Nissan Performance Innovation Task Team (PITT). The team started the drive from the test course at Nissan’s Tochigi Plant at 3:30 am. The Skyline drove through the Tohoku Expressway, Tomei Expressway, and Meishin Expressway with Kyoto as the turnaround point, and arrived at the finish line at the Nissan Technical Center in Atsugi at 8:54 pm, nearly 17.5 hours later on the same day.
The team experienced a variety of driving conditions including traffic jams from rush-hour congestion and construction.
New-Generation VQ Engine Briefing (Nissan)