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A Guide To Fuel Efficient Driving — Part Three (2022 Update)

Thanks to Covid-induced supply chain issues and Russia’s war with Ukraine, oil prices have surged to over $100/barrel at times. That and the dearth of refining capacity (converting crude oil to gasoline/diesel) has pushed the price of gasoline and diesel to record highs. One way to combat these prices is conservation — the less fuel we use, the less fuel we need to pay for, and if everyone uses less fuel then the price of oil will drop. Russia was supplying about 11% of the world’s oil and the lockdowns of 2020 due to Covid-reduced fossil fuel demand of about 20% brought the price of oil to zero (for a short period). This demonstrates the principle of conservation crashing prices and defeating fuel price inflation.

If every driver on Earth adopted the best practices of this article series, then we would cut fuel use by more than Russia was supplying to the world market and would thus bring the price of oil back to sanity. And it would cut carbon pollution, buying us more time to ramp up EV production.

This is a 3-article series. In case you missed them:

Part One – Vehicle Purchase and Maintenance

Part Two – Driving Behaviors

Summer-Specific Advice

Air conditioning will increase your vehicle’s fuel usage. The difference is likely between 5–15%. Not nothing, but not enormous. According to various tests, it does use less fuel to close your windows and use the air conditioning, but only on the highway. Though this varies to some extent by vehicle model and the rate of solar gain, which is not constant — heatwave days will definitely use more fuel for example.

Some, if not most, recent vehicles will have infrared reflective (IR) glass to reduce AC load. Tinting can also help here if your vehicle does not have IR reflective glass, but it does reduce visibility (though, is legal in many locations up to a certain level of opacity).

Spring weather improves mileage over winter weather and summer weather increases it still. Fuel efficiency increases up to about 30°C (86F), however AC use does reduce it. You can also reduce AC use by timing your trips for early morning or evenings to reduce AC load when possible.

A popular saying is that when driving in the city open your windows and close them up on the highway. Also opening windows on both sides of your vehicle car works far better than just opening windows on one side due to cross-flow ventilation.

Winter-Specific Advice

Winter means cold and in many places snow and ice. Colder temperatures makes automotive fluids more viscous, which takes more energy (hence fuel) to overcome. Additionally, colder tires require more energy for the same flex (all tires flex in operation, partially absorbing bumps, supporting the weight of the vehicle and its occupants, and providing grip). In addition, there are several other factors, as talked about below.

Winter tires add road friction and reduce mileage but provide extra winter grip, which prevents accidents and saves lives. Install them when the average outdoor temperature gets below 7ºC (45F), and in spring change them back to regular tires once the average temperature again gets above 7ºC (45F). This is to reduce their wear rate, which accelerates rapidly at high temperatures. Also, changing them back to regular tires gets you back to maximum fuel economy. Finally, all-season tires are informally known as “does all seasons badly” tires. They are not a replacement for winter tires if you live in a location that gets more than a dusting of snow each winter.

Keep your car clear of snow and ice in winter to maximize aerodynamic efficiency. Foam snow brushes with rotating heads are amazing at removing snow from the roof and windows and hood/trunk, and they won’t scratch the paint.

Driving in rain, and more so in the snow, adds rolling resistance. It’s surprising how much extra energy is taken up displacing snow with tires when the road is not clear. This also applies to gravel roads, potholes, driving through mud/dirt or sand and so forth. This inefficiency is hard to mitigate beyond taking a different route, except by trying to avoid trips when there is accumulated snow on the roads and waiting until the roads are clear (if practical, it’s not likely a workplace will accept this as a reason for not coming in). Also see if your city has a pothole reporting system.

Wind resistance, especially on the highway, is much higher in winter because colder air is denser than warmer air. And in many areas, winter has more wind than spring/summer/fall. Thus, headwinds cause an extra gas penalty and tailwinds give less of a savings.

In an ICE vehicle, warming up the passenger cabin does not use much additional fuel, as the heat for the cabin comes from waste heat produced by the engine. The slight extra energy use is just for the fan to move the heat from the heater core into the passenger area. That said, some ICE vehicles have ceramic heaters so that you can get heat right away without waiting for the engine to warm up. In this case, you will save a couple percent by waiting until the engine is warm, if you can handle the cold for that long.

Heated seats, on the other hand, use electricity produced by burning fuel — hence, they do lower economy a bit. Of course, this is a comfort vs. fuel consumed calculus on your part. If your vehicle has ceramic heaters for instant heat on a cold engine, then the heated seats are more efficient. If not, then using heated seats only until the engine provides enough heat is a reasonable way to get heat faster with reduced penalty.

In an EV, cabin heat does reduce range in winter because engine inefficiency is not available for exploitation. For these vehicles, heat makes a very measurable difference, but heat pumps are becoming common and can cut this penalty by 50% or more. Precondition your vehicle if it’s plugged in so that it’s warmed up from the grid vs from the batteries. Heated seats are more efficient in an EV vs. circulated heat since you feel warmer in a heated seat than warmed air that takes time to warm up the vehicle’s interior. For a fossil-powered vehicle using engine heat, this is not a fuel savings.

With shorter days and darker nights, headlight and taillight use will be higher. This adds a few percent to fuel consumption. However, there is not much you can do to mitigate this besides attempting to do more of your driving in the daytime, which is safer anyway. LED headlight replacements will cut this use quite a bit, but most retrofits are not street legal in most countries because the beam pattern sucks compared to stock and often blinds other drivers, and/or the throw pattern does not match the OEM halogen design and you don’t get light where you need it even if the much higher claimed lumen counts are not fake. So, don’t bother with them. Headlight housings are designed to collect, collimate, and project light based on the beam pattern of the OEM light source (the bulb type chosen by the manufacturer). LED bulbs have a different throw pattern because of the underlying technology, hence are incompatible with housings designed for halogen bulb beam patterns. If the housing was designed for the LED throw pattern at the factory, then retrofit could be successful, but until this happens, stick with OEM bulb suggestions. Finally, you can get higher brightness halogen bulbs, but the technology has a wrinkle — higher brightness comes from a thinner filament, which means much shorter life. In some cases, the extra bright bulbs can last 6 months or less, versus many years for the regular filament bulbs. Also, there are no energy savings to be had here — the wattage is the same.

An integrated engine block heater will reduce the warm-up penalty talked about in Part Two. By using a block heater to reduce warm-up fuel, you are in a sense trading some carbon/money from fossil fuels for much cheaper electricity, which is also typically lower carbon intensity (and getting greener in most countries as time goes on). Use the block heater whenever possible if you have a plug handy and your vehicle has a block heater. If it does not, see if one can be retrofitted by the dealership. The colder the outdoor temperature, the greater the positive impact from the block heater. Typically 1-2 hours of block heating is sufficient to gain maximum benefits. Below -20C, add an extra hour or two. Never forget to unplug it before travel or the cord can damage your bumper, which can be expensive to repair.

You don’t need it plugged in 24/7 which will waste electricity, so use a timer if necessary, which is not expensive to buy at a hardware store or Amazon.

The block heater can reduce your fuel use by 5-40% depending on temperature, amount of heating and length of your trips.

Miscellaneous information:

  • Some cars have an Eco mode that causes slower acceleration and sooner up-shifting unless you mash the pedal. Some even have an Eco indicator that tells you when you are driving efficiently. Use both of these if your vehicle has them.
  • Ethanol and winter gas reduce mileage slightly. These are hard to avoid. E85 reduces mileage greatly but is rarely sold.
  • Avoid drafting (tailgating) other vehicles or transport trucks/lorries. This does improve your mileage, but the risk of injury (not to mention flying debris such as sand and rocks) is not worth the fuel savings.
  • People like to drive in convoys. We have an instinct to travel together. On city streets or highways that are not crowded, you will notice groups of vehicles traversing together. This does provide some unintentional fuel savings, as aerodynamic resistance is slightly shared between vehicles, but it also means a lot more accelerating and braking to maintain the convoy, which reduces efficiency, and increases the potential for multi-vehicle accidents. In general, fight this natural inclination and travel away from other vehicles. This also gives you more reaction time and you can travel at a more fuel efficient speed.
  • Where you park your vehicle can also affect fuel efficiency. A carport or unheated garage will keep snow and ice from interfering with the aerodynamics, in cold weather a heated location will reduce warm up losses, during summer parking in the shade will reduce how much work the AC has to do to cool down the vehicle and keep it cool, and so forth.
  • If your vehicle has idle-stop technology then don’t creep forward once you stop at a traffic light or elsewhere because this restarts the engine then you move a few feet then shut off the engine again. This adds unnecessary wear and wastes startup fuel (in general restarting an engine uses 10-15 seconds of idling fuel). Conversely, if the car is not needing to move for more than 10-15 seconds and is parked (not at a traffic light or on the road), turning off the engine will save fuel.
  • For many automatic transmission vehicles, putting the car in Neutral/Park instead of leaving it in Drive can cut idling fuel use by 15-25%. This can be tested with the OBD2 dongle/Scangauge mentioned in Part Two. Of course make sure you put the car back in drive or else you will rev the engine hard and go nowhere once you try to move again while wasting a bunch of fuel (more than you saved). Also, if your vehicle already has idle stop, then Neutral/Park won’t save you any fuel.
  • Oil and fluid changes don’t tend to increase mileage by much. Even synthetic fluids make very little fuel economy difference. However they can greatly accelerate component wear if not replaced on schedule.
  • Don’t use drive-throughs if you can avoid them. 5 minutes of idling at 2L/hr or 0.5 gal/hr (an average idling consumption) uses 0.16L of fuel (0.04 gal). 10 minutes of idling doubles this and so forth. On a cold engine and short round trip distance you can get less than 1/4 of your vehicle’s rated fuel economy!
  • If you have the option to work from home part time or full time, then this will cut your fuel use dramatically.

Traffic lights not being synced can increase city fuel consumption by 20-75% or more! However virtually no one is tackling this easily solved issue. Consider contacting your city’s transportation department or sitting in on council meetings and raising this issue, writing letters to the editor, post on your city’s social media pages, speak with your mayor and more. They may complain about the cost, but frankly that’s a cop out, as they would use staff they already have and can add this job to their roster.

Ideally traffic lights should be synced to the speed limit and this information should be put up in signage so people know they can go the speed limit and save fuel by getting all green lights.

Also more people asking for the same thing tends to get better results than just one person asking so get people you know to accompany you or to contact the municipality themselves or start petitions and more.

And even consider running for office if that’s what it takes to solve this issue. And once elected you can also lobby for electric vehicles and chargers.

Finally, send this article to everyone you know 🙂

In conclusion, these are the broad strokes to driving your vehicle for greater fuel efficiency. There are other niche tactics such as pulse and glide, but they get more complicated and can endanger the safety of yourself and other drivers and should be avoided. Finally, don’t forget about the possibilities of carpooling or working from home. The most efficient way to operate your vehicle is to leave it at home whenever possible.

By following all the recommendations in this article series, you can reduce your fuel consumption by 20-50% depending on your use pattern, how well you use the techniques applied, and taking into consideration what percent of your mileage is city vs highway miles. If every driver on earth followed the lessons from this series, oil prices would crash.

In case you missed them: Part One and Part Two of this series.

The standard disclaimers apply. All advice is for informational purposes only — CleanTechnica is not responsible for any damages caused by inaccurate information, and the user assumes all risks of following any advice provided.

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