MCE-5 VCRi: Pushing back the fuel consumption reduction limits

We don’t need VCR to improve
engines since other solutions exist

VCR will be a new part of the technological mix
applied to internal combustion reciprocating engines

In 2010, a Toyota Yaris has the features and
the level of sophistication that were reserved
for top-of-the-range cars 20 years ago

It makes as little sense to say that we can get by without VCR as it is to say that we don’t need gasoline direct injection, turbochargers or VVTs. None of these systems is strictly indispensable when building an engine. Taken separately, we can get by without each of them but at the cost of a real decrease in energy efficiency, which goes against current objectives.

What’s more, eliminating certain technologies challenges the usefulness of others due to the different interdependent relationships. For example, gasoline direct injection makes no sense without turbocharging and vice versa. VVTs, considered as luxury equipment in the 80’s are now considered as basic engine equipment, like a refrigerator is part of the basic equipment in a kitchen.

The trend today is to pile up technologies. This is necessary in order to deal with major environmental and energy challenges. Piling up technologies results in piling up costs. Yet, the reduction in the unit cost price of these initially expensive technologies has made them affordable for smaller cars. On this account, the piling up of costs did not result in a proportional increase in the cost price of vehicles. Today, a 10,000 € car is generally equipped with multipoint fuel injection, one or two VVTs, a 3-way catalytic converter, ABS, power windows and air conditioning. No one would want to go backwards, and on the contrary, the level of equipment and the sophistication of vehicles will be much higher in future. Vehicles are more costly in absolute terms but less costly in view of their technological content.

VCR will contribute to improving engine efficiency in the same way as gasoline direct injection and turbocharging. VCR will not replace GDI or the turbo; it will cooperate with them and add new leverage to generate greater efficiency. VCR will become a new element of the technological mix used to design engines. Hence, VCR will make new technological combinations possible, each offering a different cost/benefit ratio, more or less adapted to the target vehicle. For example, in certain cases, it will be preferable to plan for a MPFI VCR engine since its cost/benefit ratio will be better than that of a GDI VCR even with higher absolute fuel consumption. The choice of the best combination explains why we don’t put all the existing technologies in vehicles, which could provide the highest fuel efficiency. The “full option” engine is more for high-end vehicles for which customers are less price sensitive. VCR will become a new element of energy efficiency optimization but also economic optimization.

VCR will be necessary to obtain the highest fuel consumption reduction. VCR will also be an essential optimization component for many vehicles to reach the best cost/benefit ratio. As a result, VCR cannot be replaced by another technology, which is already the case for VVT, turbocharging and gasoline direct injection.