| Our previous article talks about careful planning in order | | | | Diesel engines are about 30~35% more efficient than |
| tosave unnecessary trips, adopting carpooling to share | | | | gasolineengines. New advances in diesel technologies |
| out thecosts, avoiding traffic jams at peak hours to | | | | and fuels aremaking these vehicles more attractive. |
| avoidunproductive burning of fuel, avoiding carrying | | | | Accessories like air-conditioning, power steering, |
| unnecessaryloads and other tips that will help in some | | | | windshieldwipers, and others use the energy |
| way or another tosave on fuel consumption. | | | | generated from the engine. |
| I did touch a bit on more efficient smaller cars that | | | | These use up to 2.2% of the energy. Efforts in |
| arelighter and do not have to carry excess and | | | | developing moreefficient alternator systems and |
| unproductive weightsin their frames, chassis and body. | | | | power steering pumps canimprove the fuel economy |
| However, very often, thesesmaller and lighter cars are | | | | by up to 1%. |
| not as comfortable to ride comparedto the heavier | | | | Driveline losses can account for up to 5.6% of the |
| ones. | | | | total. Theenergy is lost through the transmission and |
| So, in this article, I won't compare lighter cars with | | | | other parts of thedriveline. To reduce these, |
| heaviercars. I will explore with you the kinds of | | | | technologies such as automaticmanual transmission |
| efficiency lossesthat are quite typical even within the | | | | (AMT) and continuously variable transmission |
| same class of cars. | | | | (CVT) has been developed. |
| If you look through the sales brochures of new cars, | | | | Next comes the shape of the vehicle. Aerodynamic |
| very oftenyou can find figures that indicate the fuel | | | | drag accountsfor 2.6% of the energy losses. As the |
| efficiency of thecar. With that information, you can | | | | speed of a vehicleincreases, the drag caused by |
| compare and find out themost fuel efficient vehicle | | | | expending energy to push air outof the way increases. |
| that will meet your needs. Evenwithin a specific size | | | | By designing the shape of a vehicle forsmoother air |
| class, there is a tremendous range of | | | | flow, significant drag reduction can be achieved. |
| MPG (miles per gallon) performance that you can find. | | | | Rolling resistance is another loss encountered in a |
| Just for example, for the same model year compact | | | | vehicle. Itaccounts for 4.2% of the losses. This rolling |
| cars, we canfind fuel efficiency ranges from 21 to 48 | | | | resistance is ameasure of the force necessary to |
| MPG. If you choosethe 48 MPG car, you could be | | | | move the tire forward. Tocounter this, tires |
| saving hundreds of dollars in fuelcosts each year. I | | | | technologies like thread and shoulderdesigns, and the |
| think that should be an important point tonote when | | | | use of improved materials on the tire belt andtraction |
| buying a new car. | | | | surfaces are being developed. |
| Having decided on the model that fulfils your needs, | | | | For passenger cars, a 5~7% reduction in rolling |
| you mightbe interested to know where the energy | | | | resistanceincreases fuel efficiency by 1%. However, |
| goes. | | | | these improvementsmust be balanced against traction, |
| Idling losses could account for as much as 17.2% of all | | | | durability and noise. |
| thelosses. In urban driving, this much of energy is lost to | | | | Related to the driver's behavior is braking loss. This |
| idlingat stop lights or in the traffic. There are | | | | canaccount for as much as 5.8%. Each time a vehicle |
| technologiesavailable such as integrated starter / | | | | moves forward,the vehicle's drivetrain must provide |
| generator (ISG) systemsthat help to reduce this type | | | | enough energy to overcomethe vehicle's inertia. This |
| of losses. It does this byautomatically turning off the | | | | inertia is directly related to theweight of the vehicle. So |
| engine when a vehicle comes to astop and restarting it | | | | for lighter vehicles, less energy isexpended to |
| instantly when the accelerator is pressed. | | | | overcome the inertia of the vehicle compared to |
| Another very significant loss is through the engine itself. | | | | aheavier vehicle. The less a driver brakes, the less |
| Theinternal combustion engine of gasoline-powered | | | | energy isexpended to move the vehicle again. |
| vehicles is veryinefficient. Over 62.4% of the fuel's | | | | As you can see, there are many factors that can |
| energy is lost through theengine combustion process | | | | affect the fuelefficiency even of similar vehicles. |
| of converting the fuel's chemicalenergy to mechanical | | | | Factors like the vehiclecondition, tire pressures and |
| energy. Energy is lost to engine friction,pumping of air | | | | design, driver's habit, planningtrips, reducing excess |
| into and out of the engine, and removing thewasted | | | | loads, avoiding drag, idling at peaktraffic and many |
| heat. | | | | others can affect the efficiency. |
| Advanced engine technologies have been developed | | | | With a better understanding of the measures you can |
| to addressthese losses. Some of them are: variable | | | | control, youshould be able to achieve the best optimum |
| valve timing and lift,turbocharging, direct fuel injection, | | | | efficiency in yourvehicle and save money in the |
| and cylinder deactivation. | | | | process. |