One major complaint of car manufacturers objecting to the new fuel economy standards is that the technology to achieve higher mpg is either too expensive or does not exist. There are plenty of existing technologies that already exist, and in some cases could be a simple software fix that could potentially improve fuel economy without decreasing power, such as:
- Stopping the engine, or reducing the number of cylinders firing when the accelerator is not depressed
- Only engaging the alternator when the car is slowing down or the battery needs more power
- Cooling the intake air
The above changes could be implemented without full platform changes, and could provide significant improvements in fuel economy. Stopping the engine at rest or when the accelerator is not pressed could cost additional money, as there could be additional overhead necessary to restart the engine. However, existing computer technology already in the car can control the fuel and air mix, which could potentially be set to zero for most of the cylinders, using only enough gas to keep the engine from stalling.
For many cars, the alternator is engaged all the time, even if the battery is fully charged. Mechanical energy from the engine is converted into electrical energy when the alternator is spinning. If the alternator is connected to the engine, it diverts energy to the battery, taking away from the energy being used to propel the vehicle forward. Detaching the alternator when not needed would increase fuel economy. Re-engaging it when decelerating would be a poor-man's equivalent of regenerative braking, and would recapture energy that would otherwise be lost when stopping. Unfortunately, as more electronics are added to a vehicle's interior, battery power becomes more necessary, reducing the payback of this measure over time.
Cooling the intake air is something that would require some internal changes to the engine, but is readily available cheaply. Cooler gases expand more than hot gases when the engine fires, increasing the total power produced for the same amount of fuel.
While auto manufacturers are correct in that additional development means additional cost, they strategically omit the fact that there are additional things that can be done with today's technologies at relatively low cost.