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How to Check the Energy Efficiency of a Car

Experiment: To check the Energy Efficiency of a Car


A car is the basic need of transportation used by many people in multiple countries around the world as it offers a high level of comfort than any local transport readily available. Unfortunately, car innovation depends on its internal combustion, which creates high contamination levels in the most populated regions worldwide, which may lead to a hazardous atmospheric deviation. Along these lines, enhancements in proficiency would decrease its negative effect on nature (Herring & Roy, 2007). There is the EPA, which is used to measure the car’s productivity as for electric vehicles. It is also known as MPGe or “Miles Per Gallon Equivalent.”



MPGe is used to measure how​​ far a car can travel on its battery energy comparable to the gallon of the gas it contains. Here we are attempting to​​ experiment on a vehicle and analyze how​​ energy productive it is. The experiment will be done on the world’s most fuel proficient car by checking its motor limit and fuel utilization.​​ The​​ experiment performed is done on Volkswagen Lupo 3L, which is designed efficiently​​ in fuel consumption. It weighs 830kgs with a three-cylinder 45kw diesel engine. It also holds a record for world four-seat fuel economy cars at 78 miles per gallon (Roura & Oliu, 2012).

Discussion of Theory

The Thermal Efficiency of Engine:

Since most cars can be measured based on their fuel usage, I decided to perform this experiment by choosing a specific vehicle based on its "balancing of energy." I composed basic experiments given essential material science and discovered very agreeable outcomes. In the perspective of this relative achievement, I trust my investigation will be helpful for other students as well​​ in the way that if they ever have any experience to check the energy efficiency of any latest car’s they came to know about the circumstances I had gone through while performing this experiment.

Even though the experiments are based upon elementary physics, by doing the complete analysis of the results achieved, it comes to know that it requires all​​ the knowledge of the concepts of the introductory courses of the mechanics, which are rolling resistance & thermodynamics. (Roura & Oliu, 2012)

The effectiveness of any thermal engine can be found by looking at its fuel usage between the upward and descending bearings of a few street segments while moving with the fixing apparatus with the most consistent speed, the tools such as “AVL Consumption Measurement” are used for such purpose.​​ According to Herring & Roy (2007) and Roura & Oliu (2012), the upward work done by the engine can be found with this equation:​​ 

Wu=Ee+ ER+ ED+ mgh

In Equation, the "Ee" is just the mechanical engine's losses, which can be said as the subbing of the few parts while in motion,​​ like pumping of fuel, the​​ rubbing of some features that associates the engine with the rigging box,​​ etc. The "ER" tells us about the losses created because of the twisting tires, which also use in grinding of some parts while associating the car's wheels​​ along with the rigging box.​​ ED"​​ is​​ because of the losses created by the air protection,​​ and​​ the​​ "mgh"​​ is the potential adjustment in the energy of the car alongside the traveller (Chau & Chan, 2007). When the work is done is calculated in a downwards direction,​​ WD," the same value is taken by the drag, taken as in the upward trend. It is because the speed of the car is identical, so it is quite acceptable to assume that​​ Ee þ​​ ER​​ approximately, and it will remain the​​ constant.​​ Slight​​ contrasts may emerge​​ because the inner powers and torques are higher​​ on​​ the upward way.​​ 

Finally, the potential energy change will reverse its sign, basically the reverse motion of the potential energy in the above equation, which is​​ much.​​ Subsequently, the estimated fuel consumption difference (Fuel consumed/distance by the engine) in between the upward as well as downward direction is

c=cu-cd=1ηWu-WdQFd= 1η2mghQFd

The Cycle of expansion & compression is followed by the diesel engines, which is very close to the diesel cycle ideally. The massive duty engines such as trucks & generations with electricity are expected to deliver more than 40% efficiencies. This is because of the higher pressure used in, the larger machines, but the efficiency measured by me for the engines of light-duty is quite different and high.

Unfortunately, I can’t​​ find any published data to​​ compare the efficiencies of the commercial car's engines​​ to any other such experiment that had been done previously.​​ Furthermore, there's the fact that a higher deviation from the thermodynamics' reversibility corresponds with shorter cycles. The combustion engines' thermal efficiencies within a broad range of frequencies are used to remain almost constant.

So,​​ we can say with the 3700 rpm, the efficiency decreases because of the deviations, but it is higher in terms of the ideal diesel cycle instead of reversibility. Moreover, in any case, the 'g' consistency should not extend the reader's conclusion because it is incorrect & erroneous. It states that the total engine efficiency depends on gear & velocity.​​ What must​​ be taken into account is the engine’s mechanical losses (Ee) as it is used to evaluate the machine's overall efficiency (Amara et al., 2006; Roura & Oliu, 2012).

Energy Balance & the Efficiency of the​​ Brakes

The result of my experiment allowed me to experience the consumption of fuel usage. I came across to know why at 2000rpm, the consumption with the 80km/h is higher than at 50km/h. Furthermore, with 2700 rpm, the consumption with the 80km/h is lower than at 50km/h. Another essential thing to consider is the car's size and engine power; renowned publishers have shown that commercial cars' fuel consumption increases by 32%, increasing its mass by 50%, mainly by keeping its power constant per unit mass. We won't find it surprising if we look at the proportionality of braking losses on group & the rolling resistance.

Additionally, a 17% increase in fuel consumption and 50% in the engine power for the same mass (Marshall, 2008). ​​ We do not know what the primary origin of this relationship is. It seems like it's because of the mechanical losses of​​ the engine. There is no doubt that in this whole study, the car's size is small, which contributes chiefly towards making this car positively fuel-efficient.​​ 

This section is concluded with two facts. Firstly, American cars' fuel economy has gradually increased in 25 years by 15% due to continuing innovations in technology (Roura & Oliu, 2012). It means that the consumer enjoys the design of the increasing car size & power, but they didn't have a good effect on the cars' environmental impact. Secondly, the average fuel consumption rate was decrement by 3.7% in Europe's vehicles in 2010. Later on, it is estimated that there is a 5% reduction because of technological innovation, which happens due to the increment in the car's size.


Only the car and some measuring tools are used to experiment.

​​ If we're testing the car's fuel efficiency, shouldn't we be experimenting with some comparison? Maybe with another vehicle that doesn't fuel efficient? ​​​​ 

As discussed previously, I'm experimenting on the most awarded fuel-efficient car to check the primary reasons that make it more & more efficient and depend on examining the car instead of any comparison.


The experiment is done by carefully examining​​ the efficiency of the car. I’ll perform this by driving and​​ measuring​​ via​​ its Rpm. Additionally, I​​ read the engine capacity by carefully doing the calculations with the given formulas, as discussed in the above section​​ after​​ the experiment is performed.


In the observation, I want to discuss the fuel economy of the car, which is too high, as we have seen in the study to​​ show that the size of the vehicle and​​ its engine power play a vital role. Some of the innovative strategies may​​ reduce​​ some of the work which is needed to​​ improve the car’s efficiency:

  • The optimal aerodynamic design​​ could have​​ reduced​​ the air drag.​​ 

  • The tires of​​ lower mechanical hysteresis could​​ have minimized the rolling resistance.

  • The energy used to accelerate​​ the car​​ (meant by braking losses) is lowered​​ by using the low-density metal alloys & fibre-reinforced plastic​​ composites in several components.​​ The car engine does all of this work, & the​​ engine​​ efficiency depends on its mechanical losses​​ & the heat generated.​​ 

The car we are experimenting​​ with has low heat loss, which is a clue for its high fuel efficiency (Roura & Oliu, 2012).

The car-size & engine power is essential. It has been found out that the consumption of fuel is increased by 32% of the commercial cars whenever their mass is increased by 50% when its power is kept by unit mass constant.

There's no surprise in this dependence about the proportionality of braking losses on mass & the rolling resistance, plus the force of air dragging on the vehicle's cross-section. However, with this mass, there is an increase in the fuel consumption of 17% & for the power of an engine, there's an increase of 50%. In spite, this relationship's primary origin is​​ not precisely known, but​​ it's probably because of the engine's mechanical losses. There is no doubt that the car's small size in this experiment plays a vital role in providing high fuel efficiency. Let's sum up this section with two facts.​​ Without some innovative technology change, the average American car's fuel consumption increased by 15% from 1980 to 2005. This revealed to us that any of the advantages which the technology gives were coordinated at the consumer by expanding the power & the size of the car. They have a minimal impact on reducing environmental issues by the car. Secondly, in 2010, the average vehicles sold in Europe have witnessed a 3.7% decrease in fuel consumption. Later on, it is estimated that there is a 5% reduction because of technological innovation, which happens due to the increment in the car's size.


​​ A test is conducted to estimate the commercial car energy proficiency. I have performed a trip to observe why the car is so fuel-efficient. The vehicle's thermal​​ efficiency​​ is resolved around 40%, which is the value that is free of the frequency; this is because​​ by carefully examining each​​ measurement done during the experiment. Moreover, the cars designers should focus on the details highlighted here about the car size, which affects its consumption to improve future work.​​ Incorporating everything, my experience is that​​ only​​ technology doesn't lessen cars' effect on the environment. Constraining the car's size and energy of the vehicle is also essential.


  • Chau, K. T., & Chan, C. C. (2007). Emerging Energy-Efficient Technologies for Hybrid Electric Vehicles. Proceedings of the IEEE,95(4), 821-835. doi:10.1109/jproc.2006.890114​​ 

  • Amara, Y., Vido, L., Gabsi, M., Hoang, E., Lecrivain, M., & Chabot, F. (2006). Hybrid Excitation Synchronous Machines: Energy Efficient Solution for Vehicle Propulsion. 2006 IEEE Vehicle Power and Propulsion Conference. doi:10.1109/vppc.2006.364367

  • Herring, H., & Roy, R. (2007). Technological innovation, energy efficient design and the rebound effect. Technovation,27(4), 194-203. doi: 10.1016/j.technovation.2006.11.004

  • Roura, P., & Oliu, D. (2012). How energy efficient is your car? American Journal of Physics,80(7), 588-593. doi:10.1119/1.4704821

  • Marshall, J. D. (2008). Energy-Efficient Urban Form. Environmental Science & Technology,42(9), 3133-3137. doi:10.1021/es087047l


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