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How carmakers use less fuel to reduce emissions

mpg or l/100 km
mpg or l/100 km

On the road to marketing the next alternative transportation model after the last ‘new and improved’ version, every automaker is working to reduce fuel consumption in various ways.

The most noticeable methods are engines with less cylinder volume (capacity) and/or reducing the number of cylinders.

Numerous other techniques are being incorporated, each one gaining a small percentage improvement. Adding up all the little ‘tricks of the trade’ helps bring down fuel consumption and emissions.

As you may have heard, Gasoline Direct Injection (GDI) is one of the latest techniques employed to cut down on the ‘bad stuff’, fuel consumption and the resulting corresponding emissions.
Transmissions with ratios between six and ten (!), depending on the type of engine and model of car will save approximately 10%.

Every small percentage point gained means less petroleum used; very strict consumption / emission rules will apply only six years into the future (2020) for Europe and five years later for North America. Greenhouse gas (GHG) emission, closely linked to consumption will be regulated as an average of all models produced by each automaker. (i.e. fleet average)

The limits for European vehicles will be 95 g/km of GHG, which equates to 4l/100km on gasoline, or 3.6 l/100km on diesel fuel. That is 57.4 mpg in the USA measurement.

In the USA the strict rules will take effect in 2025. We assume Canada will follow suit, according to the metric system, but short of dissecting this 65 page document we put our faith in the EPA. Because larger vehicles, pickups and SUVs, rather than compact cars make up the vast majority of vehicle sales in North America, the fuel consumption will be lowered to just 54.5 mpg; that is the equivalent of 100g/km of GHG.

The higher the mpg number, the lower the fuel consumption — that confusing fact is the reason we use liters/100 km; the lower that number, the lower the consumption, and that seems logical.

Back to the percentages of savings now: The list given by different manufacturers varies considerably, and when adding up all those percentages, they add up to more than 100% — obviously, all these savings cannot eliminate the use of gasoline. It seems that the savings are based on some baseline, but that is not indicated.

Regardless of how much is feasible, there is much potential for improvement hidden in the internal combustion engine (ICE).

This is an uncompleted and changing list of potential fuel savings and emission cutbacks utilizing various technologies as compared to the standard:
• Hybrid-Electric propulsion, in its various forms ~30 %
• Natural gas engine, the alternative to petroleum ~25 %
• Diesel engine, better volumetric efficiency ~20 %
• Pre-programmed navigation systems ~15 %
• Engine down-seizing & super /turbo charging ~12 %
• Multi-speed, computerized transmission ~10 %
• Start-Stop function and coasting ~10 %
• Internal engine refinements in materials and management ~ 6 %
• Tires with low rolling resistance / cylinder de-activation ~ 5 %

An even larger percentage of savings could be possible from saving weight; As the renowned founder of Lotus cars said, “Simplify, then add lightness.”

The articles of April 14 and 21 give an indication of that possibility.

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