I occasionally drive a 2003 Nissan Altima V6 5 speed M/T.
When I drive it, it consistently gets ~30mpg in mixed driving. When my wife drives it, it gets ~25 mpg consistently.
How do I get that extra 5 mpg or 80 miles per tank? By conserving momentum, not running the A/C, going the speed limit etc.
That's the key that most drivers don't seem to get. For instance, tailgating wastes fuel, because it makes it difficult to conserve momentum.
Hitting the brakes turns kinetic energy into heat at the brake discs/drums. IE coast and keep braking to a minimum.
Automatic transmissions, preferred by Americans, are also inefficient in some ways, such as idling in D, the engine is pushing against the brake (torque converter slipping). People with auto transmissions can save fuel by shifting to neutral when they are stopped, but most don't. The savings are small, but just like building a performance engine, every little thing adds up.
I always coast in neutral on downhills or when I see that I'm heading toward a stop. I turn off my engine at long lights. I keep the engine RPM below 2500 wherever possible. Admittedly a manual transmission makes these things easier to implement.
I try to keep moving, but I don't run stop signs or take corners at unsafe speeds.
Since my car is rated 23/27, I feel pretty good about averaging 30mpg in mixed driving. And yes, the MPG meter was very helpful in me learning how to maximize the mileage in THAT car. I wish my other car had one.
Any car can see similar gains percentage-wise, if their drivers stopped thinking about "me here me go there" and started thinking about how chemical energy is wastefully converted into momentum by the gasoline engine (~30% eff), and again converted to heat by the brake system.
I tell my wife, to no avail evidently, to think of it like you were riding a bicycle. When biking we naturally conserve momentum because were are intimately aware of the energy required to accelerate from a stop.
As a result of her less efficient technique, she usually drives the TDI Jetta 5 m/t(averages 43 mpg) , and I mosey along in my Pre-PO awareness Altima, maximizing its miles per gallon at all times. I'm able to get almost 50mpg with the Jetta, but a quick break-even analaysis reveals that I should be driving the Altima, as she drives more than I do each day.
Just because an engine makes high hp/cubic inch, doesn't mean that it can't be driven efficiently. My friend has the same car (Altima 3.5SE) with a 5 speed automatic trans, and never gets more than 23 mpg. Part of that is due, I'm sure, to the fact that he always runs the A/C, and drives like most people: hard on the gas, hard on the brakes, tailgating,ad infinitum.
One thing I've learned in a lifetime of hot rodding, racing, restoring, and driving cars is that speed costs money. How fast you go depends on how much you're willing to spend. Me, I am not willing to spend much any more, therefore I go slow...
.. much to the consternation of many of my fellow drivers.
I keep expecting to see signs of other people grasping this concept, yet on a 350 mile road trip two weeks ago, where I drove the speed limit the whole way, I passed only 6 cars, and was passed by hundreds of SUVs, cars, and semi-trucks moving in excess of 80 mph.
In theory a 55 mph speed limit would help, but in reality it would result in increased revenues for various police departments and for auto insurance providers, as most people have a callous disregard for the speed limit or so it seems. I used to be one of them until PO woke me up.
Just my 2¢
). I basically never use jackrabbit starts, coast quite often in neutral if I'm somewhere on a 6 lane interstate with a long, long downhill, or coming to a stoplight, keep rpms below 3000 on the truck & 4000 on the Miata (high-revving engine).
Like a steam locomotive, rolling down the track
