They don’t want you to know these facts about getting better gas mileage.
It’s true.
Probably because they let other considerations get in the way of The Truth, like, for example, safety…
You judge for yourself, as we go along.
I’ll try to present each topic in order of most gas savings down to least, but it’s a hard-to-quantify best guess in many cases… I am focusing on what you can do with your current automobile (and without major car surgery) to get the very best possible gas mileage from it.
Don’t Stop. Ever…
Momentum is your friend, it’s how your car stores most of its energy from those expensive gallons of gas. When you are in motion you are at the lowest friction state that you car experiences (and friction is the eater-of-gasoline). Your brakes work by applying friction, and hence eat gasoline.
By way of test, my car gets 0.0 MPG when stopped, around 7 MPG accelerating and over 100 MPG when coasting through a stop sign or red light. It’s a no-brainer (pun intended).
For those of a more conservative (meaning safety) bent, this can translate into taking the route with the fewest stops (and shortest duration stops too). Slowing down by coasting is far better than flying up to a stop and hitting the brakes.
Also, allowing your vehicle to speed up while coasting down into a dip or valley and using that extra stored energy to get back up the other side means dollars in the wallet (maybe used to pay the speeding ticket). Pop it into neutral to get the least engine braking effect on the way down the hill (about shutting off the engine: – it makes steering hard, braking hard and may eat as much gas re-starting as you saved. Hybrid cars are rigged to use this method constantly and hence avoid the pitfalls).
Take those turns at a somewhat higher speed instead of hitting the brake pedals – you’ll come out of the turn with more of your precious momentum intact. If you make it around the curve.
Interestingly, hard acceleration (the infamous ‘Jack-Rabbit Start’) does NOT seem to have a significant negative impact on overall fuel economy. There are a lot of factors involved here, but if you aren’t squealing your tires on take-off, a fairly brisk acceleration may well save you gas. Why? Well, it gets you to the coasting/high-momentum/low-friction state in fewer miles than a leisurely putt-putt take-off, and the fluid clutch in most automatic transmissions are slipping away quite a bit of that engine power at low torque…
Wind Resistance!
Air resistance is exponential with vehicle speed, so a moderate pace can result in much better gas mileage. Or tailgating at higher speeds, which might get you the same benefit plus shorter trip times. With large trucks on the freeway, this technique is known as ‘Drafting’.
Obviously, choose the largest available SUV to tailgate to get the best effect, such as a Hummer or Ford Expedition. Semi trucks were the drafter’s target of choice in the past, but most states require that they travel at a slower speed limit than cars nowadays, so if you want to zip along, stick with SUVs. Like a bumper sticker.
Removing sources of added air resistance, such as roof-stored ski pods in the summer, can help to some extent. Tail winds are a great help too, and the stronger the better – surfing on a storm’s gust front ought to be a great mileage booster.
Leave those windows up at higher speeds – above 35 MPH (50 KPH). If you must be cooled, use the fan. If that’s not quite enough, AC is better than the windows down at freeway speeds. Um, unless you are drafting.
Water on the road adds a lot of resistance to rolling, so avoid rainy weather for best mileage. Curiously, water adds a bit to your ‘octane’ of your fuel which can help with fuel economy… this effect may offset wet-road losses to some extent.
Accessories
The power you use to light the road ahead and behind you is generated by the alternator. The drive belt on the alternator steals power from the engine. Hence, having those daylight running lamps lit costs you mileage!! Night driving will be lower mileage than daytime, for the same reason. Unless you keep the lights off. Wattage translates to MPG lost, so dimmer is better for best mileage. Driving with running lights when you can see at all is better than headlights on for your wallet. Hmmm… no lights and a night vision system? Maybe in the future it’ll be the norm!!
Air conditioning is not free either – robbing power from the engine to chill the poorly insulated passenger compartment (heat is alright, though – it’s waste energy from the engine, dumped into the car interior)
More and more power is consumed by accessories like entertainment systems and computers in modern cars. Shut ‘em off to save gasoline!
Weight in the car (if you can’t avoid stop/start driving) nibbles away at you mileage too, so dump the extra cargo as soon as you can. In fact, keeping the weight of gasoline down by running your tank below ½ can help your mileage.
Removable seats? Need I say what to do with them?? Extra passengers? How needs the noise as you fly around the curves anyhow?
Car Care
Soft tires eat mileage, so over inflate to save gas! The harder the better, as far as mileage goes.
Thin oil offers the engine less resistance to motion than thick, so stick with the lowest viscosity oil that you can get away with (note: this is a bit confusing with most modern multi-viscosity oils, since there’s more overlap than difference between them…) . Synthetic oils are just a smidge slipperier than nature intended, so they can help mileage a tad too.
Poorly running cars tend to eat more gasoline, and poorly working transmissions can squander gas mileage too. Modern thinking says spark plugs will last 100,000 miles – but maybe not. Check a plug, if it’s bad – change all of them.
Remember, parts are weight. Do you really need to put that fender back on? Bumpers today are nearly pure decoration, so if it’s dented and ugly – off with it!!
Fluid levels at just above minimums yield the lowest overall vehicle weight, so topping off might be detrimental to your mileage, be it gas or windshield washer fluid…
Old cars with looser joints experience lower friction than a brand new car, so keep the old one going for best mileage!
Conclusion
Yep, there’s a bunch you can do to get better mileage – as long as you ignore common sense…
