This comes up often on the many car forums I visit so I wrote a document and post it a few times each year:
I’ve always gotten better-than average mileage with my cars.
1) Anticipating traffic is probably the biggest thing you can do to save gas, save wear and tear on your vehicle and be kindler to the passengers in your vehicle. If you find yourself tapping the brakes a lot in heavy traffic, you are following too close or driving too fast. Slow down, relax and pay attention! That impenetrable pack of idiots ahead of you aren’t going anywhere fast either. When things start to move again, take your time accelerating. Instead of going from zero to 45mph and then back to zero again a couple of seconds later, try leaving more space in front of you and pacing yourself better. Try to average a 25-30mph in that situation instead by leaving braking and accelerating space ahead of you. When driving a standard, try to maintain a pace that allows you to idle in first or second gear rather than constant starts and stops that waste gas, raise your blood pressure and heat up your brakes. People WILL jump into that space ahead of you once in a while. That’s OK. DON’T let it upset you! Maintaining that cushion of space, you’ve lost maybe 20 feet which is an insignificant amount of distance in 10-20+ mile trips. It’s no big deal.
2) Tire pressures. I run my right at or near maximum and in 20+ years of driving, I’ve never had a problem doing this. Check and fill them when perfectly cold (first thing in the morning before the sun hit them) and adjust them as the seasons change. You just need to know that you will have a little less grip in most situations with the inflation this high. Running on a severely underinflated tire can feel like your parking brake is stuck on. It’s also very dangerous as the vehicle is more prone to blowing a tire. Also, skinnier rims and tires get better mileage than fatter ones because of less rolling resistance. Taller (greater circumference) rim and tire combos will effectively increase your final drive ratio and may boost fuel economy but this will throw off your speedometer by the same amount and might rub on the inside of your wheel wells. Experiment gradually and with caution.
3) Use thinnest-spec (and/or synthetic) oils in your engine and tranny. These reduce drag which will save fuel. If you are concerned about wear, replace them a little more often than you normally would. This change alone can save around 3% or more. Don’t go below the recommended weight for your engine … but don’t go above it either unless you are willing to accept the penalty in lost mileage and power.
4) Replace your ignition components (spark plugs, wires, cap. etc …) using the shortest intervals recommended. Use good quality, high-performance (but not racing) brands. Use Platinum plugs only if your car calls for them. I’ve found a good, copper V- cut plugs (NGKs) to provide the best mileage, better than platinums. Don’t waste your money on Splitfire plugs or other, similar gimmicks.
5) I get MUCH better mileage during heat waves (80-90F+) than I do during temperate weather (70F and cooler). The car runs leaner and develops less power but uses less fuel as well. My Honda Civic DX went from 38-40 mpg in the winter to 45+mpg during the August heat in MIXED driving, even with the air conditioning on. My SpecV can top 31mpg in the summer but will probably average around 28 in the winter. Expect this and factor the seasonal changes into your mileage expectations.
6) Using the A/C puts a load on the engine and reduces miles per gallon. Roll the window down at low speeds or use the vents and electric fan at highway speeds. Just don’t drive with the window rolled down at high speed. This causes so much aerodynamic drag that you are usually better off using the A/C. This brings me to aerodynamics …
7) A clean car (freshly washed and waxed) is more aerodynamic than a dirty car and this might make a difference on extended highway-speed trips. Minimize any roof-racking, etc … and forget about the do-nothing spoilers on the back of most cars. They do nothing but add weight and drag.
8) Be sure to change your air filter regularly. Dirty, restrictive air filters cause your engine to run richer (use more fuel). I used to use a K&N cone-style filter which tend to flow more and require less maintenance. Running a dirty air filter kills your mileage and running around in a rich condition can foul up your entire motor, its crankcase oil, the emissions equipment, etc … With my Nissan, I just make sure I change the filter element every spring once the salt is off the roads.
9) I don’t carry around a lot of junk in my car. This saves weight and less weight saves gas by putting less load on the motor. A lot of engines will richen-up a bit when the load reaches a certain point and this decreases fuel economy. You can go wacky and anal with this idea trying to strip your car down but between insanity and animal house is a clean vehicle without hundreds of pounds of superfluous junk in the backseat and trunk. Another way to reduce weight in your vehicle: stay single, don’t have kids and don’t date fat chicks.
10) Drive a vehicle with a standard transmission (not an automatic). They and their fluids weigh less, don’t lose any power through a fluid coupling, sometimes feature a higher final drive ratio and make you a better driver overall. Better drivers, all things being equal, get better fuel economy.
11) Use a good fuel injector cleaner regularly (2-3 times per year). Clean injectors fire a spray that is well atomized, burns more completely giving you greater power and economy as well as cleaner emissions. If you don’t believe in the bottled stuff (some are better than others), get it done professionally every 3 years or so.
12) Plan routes well minimizing backtracking while running errands. Unnecessary miles use unnecessary fuel.
13) Never use the drive-thru window at banks and fast-food places unless there are only 1 or 2 cars ahead of you. It’s better (and faster) to park and quickly run in.
