Evaluation of Idling Fuel Consumption of Vehicles Across Different Cities

Abstract

Road transportation is a dominant mode of travel in Indian urban centres to meet the travel demand. This primarily comprises two wheelers, four wheelers, three wheelers and Buses. Petrol and diesel powered vehicles continue to be the dominant fuel types in most of the cities. Especially in Indian cities, the trip lengths are often short and frequently encounter signalized intersections. In such travel conditions, the idling phase of the vehicle operation comprises a large proportion of journey time. Hence, understanding idling in terms of fuel loss offers potential towards reduction of fuel consumption. To evaluate idling fuel consumption of in-use vehicles, a total of 346 vehicles were successfully tested of different vintages and types under hot stabilized conditions using fuel flow detector. The measurements were carried out in Delhi, Bhopal, Chennai, Chandigarh, Pune, Vadodara and Kolkata. The test results show a variation in fuel consumption with regard to vehicle technology as well as among various vehicle types. The mean value of fuel consumption at idling for motorcycles was observed to be 0.14 l/h, whereas for three wheelers, car and bus it was observed to be 0.24 l/h, 0.6 l/h and 0.9 l/h respectively. Analysis of data concludes that at idling the vehicle technology has a significant influence on fuel consumption.

Full text

1
Evaluation of Idling Fuel Consumption of Vehicles Across
Different Cities
P.V.Pradeep Kumar
1
, Anil Singh 2, Niraj Sharma 3, Ravi Sekhar Chalumuri 4
Abstract: Road transportation is a dominant mode of travel in Indian urban centres to meet
the travel demand. This primarily comprises two wheelers, four wheelers, three wheelers and
Buses. Petrol and diesel powered vehicles continue to be the dominant fuel types in most of
the cities. Especially in Indian cities, the trip lengths are often short and frequently encounter
signalized intersections. In such travel conditions, the idling phase of the vehicle operation
comprises a large proportion of journey time. Hence, understanding idling in terms of fuel
loss offers potential towards reduction of fuel consumption. To evaluate idling fuel
consumption of in-use vehicles, a total of 346 vehicles were successfully tested of different
vintages and types under hot stabilized conditions using fuel flow detector. The measurements
were carried out in Delhi, Bhopal, Chennai, Chandigarh, Pune, Vadodara and Kolkata. The
test results show a variation in fuel consumption with regard to vehicle technology as well as
among various vehicle types. The mean value of fuel consumption at idling for motorcycles
was observed to be 0.14 l/h, whereas for three wheelers, car and bus it was observed to be
0.24 l/h, 0.6 l/h and 0.9 l/h respectively. Analysis of data concludes that at idling the vehicle
technology has a significant influence on fuel consumption.
Keywords: Idling Fuel Consumption, Fuel Measurement, Fuel Flow Meter
1. INTRODUCTION
Idling of vehicle refers to a situation in which a vehicles engine is running while the vehicle is
stopped. The measurement of vehicle fuel consumption at idling is essential to estimate the
total loss of fuel due to idling at signalised intersection. There are various categories of
motorised vehicles which are plying in different cities of India. The fuel used to power these
vehicles is predominantly petrol and diesel. Though use of CNG and LPG is gaining
popularity due to government regulatory policy on public transport vehicles in some of the
cities and use of CNG fuel by private vehicle owners due to economic benefits. The
equipment available with us has limited the study to petrol and diesel powered vehicles.
Efforts were made to cover all vehicle types. The study of fuel consumption at idling was
done at laboratory level by use of on-line fuel flow data acquisition system.
Idling is considered as one of the dominant operating mode in development of driving cycle
(Zheng et al., 2012). Driving cycle is a representation of a typical driving pattern of a
1
Senior Principal Scientist,CSIR- Central Road Research Institute, New Delhi,110025, India
1
pvpradeep1964@rediffmail.com
2 Chief Scientist,CSIR- Central Road Research Institute, New Delhi,110025, India
2 anilsingh1234@gmail.com
3 Principal Scientist,CSIR- Central Road Research Institute, New Delhi,110025, India
3 sharmaniraj1990@rediffmail.com
4 Senior Scientist,CSIR- Central Road Research Institute, New Delhi,110025, India
4 chalumuri.ravisekhar@gmail.com

city/region/area. Motor vehicle idling though perceived as a trivial amount of fuel use in the
overall fuel consumption by transport sector requires the least effect by policy makers in order
to get the fuel conservation benefits (Carrico et al., 2009). Various methods for fuel
consumption measurement in laboratory have been indicated (Pirs et al., 2008). Fuel
consumption measurements on vehicles are carried out indirectly by measuring exhaust
emissions and using carbon balance method to calculate fuel consumption. Use of portable
emission measurement system other than chassis dynamometer tests are used extensively for
vehicle certification using established test cycle are costly proposition for conducting few
tests for idling emission measurement. Critical evaluation of the various test methods for
measuring fuel consumption on engines has been elaborated and it is reported that volumetric
or gravimetric measurements are more accurate than the carbon balance method (Burke et al.,
2011). Alternatively use of OBD test based on getting data from Engine ECU is gaining
ground as an additional test method (Posada et al., 2013). The method adopted for idling fuel
consumption measurement in the present study is by volumetric measurement and is limited
to petrol and diesel powered vehicles. The volumetric measurement is also the method of
measurement adopted in retail selling of fuel for vehicle use at fuel filling station. The main
objective of this study is measurement of idling fuel consumption of vehicles.
2. METHODOLOGY
The methodology chosen to measure the fuel consumption of vehicle is elaborated in terms of
(i) Equipment used (ii) Cities selected (iii) Test set up and (iv) Data collection method. These
are briefly discussed in the following subsections.
2.1 Equipment Used
Three types of detector are used for testing various types of petrol and diesel powered
vehicles. They are (a) MF-2200 fuel flow detector (b) FP-214OH fuel flow detector and (iii)
FP-213S. All the three detectors (Fig. 1) are of ONO SOKKI make and have measurement
capability up to 0.1 ml (ONO SOKKI, Owner's Manual). In addition Engine RPM sensors
(Fig. 2) were used to measure Engine RPM, three types of sensors were used for measurement
of engine RPM. They are (a) Vibratory sensor (b) Induction pick up on secondary circuit (c)
induction pick up on primary circuit. They have measurement capability up to 1 RPM. For
diesel vehicle, the vibration sensor is the method of measurement of Engine RPM adopted.
Both the fuel flow detector and Engine RPM sensors are connected to the respective digital
output meters which facilitates recording of measurement second by second (Fig. 3).Besides
the fuel flow meter and digital engine meter, the voltage and pulse signal are captured through
the V-Box, a GPs based data acquisition system which integrates the fuel flow and engine
RPM data (Fig. 4).

(a). MF-2200 flow detector (b). FP-214OH flow detector ( c). FP-213S flow
detector
Fig 1Fuel flow Detector used for fuel consumption measurement in vehicles
Fig 2 RPM Sensor mounted on engine and RPM meter
(a). Engine RPM Meter (b). Fuel flow Meter
Fig 3 Engine RPM meter and Fuel flow Meter with communication port
(a). Fuel flow Meter (b). Engine RPM Meter
Fig 4: Fuel flow data acquisition system integrated with Fuel flow meter and Engine RPM meter

2.2 Cities Selected
To get a spread of different vehicle types and vintage, the testing was carried in the cities of
Bhopal, Chandigarh, Chennai, Pune, Vadodara, Kolkata and Delhi. These cities were selected
based on population and geographical representation of the city in India.
2.3 Test Set up
The test vehicle is examined for identification of fuel flow in the vehicle. Care is taken to
ensure that necessary spare fuel pipes and connectors are available for use of fuel flow
detector on line with the test vehicle. Depending on the engine technology adopted for a given
vehicle, the appropriate fuel flow detector is selected for fuel flow measurement. On ensuring
availability of connectors, fuel pipes and necessary tools for opening of the concerned joint in
the fuel line. The test vehicle is considered for fuel consumption measurement. The necessary
fuel connections for the existing vehicle are removed and the fuel flow detector is connected
on-line. The basic logic in proper fitment of fuel flow detector in the test vehicle is that fuel
once sensed by the fuel flow detector before being consumed by the engine is once again not
measured. It is to be ensured that there is no leakage of fuel in the fuel line/connections of the
engine after installation of the fuel flow detector in test vehicle. No adjustments or tampering
is done in the engine setting for the vehicle in normal circumstances. Under extreme
circumstances some minor adjustments/ setting are carried out on two wheeler and three
wheelers to ensure that the test vehicle does not stop during the test period.
2.4 Data Collection Method
The vehicle after connecting the fuel flow detector and the data acquisition system is ensured
that there is no leakage of fuel in the fuel line of the test vehicle during idling of the vehicle.
The fuel consumption measurement is carried for duration of 40 minutes. With the first 10
minutes considered for cold start and warm up period for engine to hot stabilise. The reading
of fuel consumption for the first ten minutes is not considered for analysis. The successive
readings of 10 minutes are considered as run 1, run 2 and run 3 respectively. The stop watch is
initialised for measurement of time duration and simultaneously the fuel flow meter is
initialised for measuring the total flow, the event trigger is also pressed to ensure initialisation
of fuel flow in data logger. The information related to the vehicle as indicated in the
registration certificate as well as the odometer reading as well as the information shared by
the vehicle owner are also recorded. The vehicle is operated in idling mode continuously for
the entire duration of the test.
3. MEASUREMENT OF IDLING FUEL CONSUMPTION
Idling fuel consumption studies were conducted in 7 cities including Delhi. The following
categories of vehicle with various engine technologies were considered for measurement of
idling fuel consumption.
 Two wheeler motor cycle with carburettor
 Three wheeler rickshaw with carburettor
 Four wheeler car with carburettor
 Four wheeler car petrol powered with Multi-port fuel injection (MPFI)
 Four wheeler car diesel powered with indirect injection

 Four wheeler multi utility vehicle diesel powered with indirect injection
 Four wheeler multi utility vehicle diesel powered with direct injection
 Light commercial diesel powered Truck
 Light commercial diesel powered Bus
 Heavy Vehicle diesel powered Truck
 Heavy vehicle diesel powered Bus
The number of vehicles tested city wise, fuel type and engine capacity wise are categorised
in the following sections.
3.1 Fuel Consumption of Petrol Vehicles at Idling
A total of 285 petrol vehicles includes four wheeler, three wheeler and two wheelers were
tested at different cities. Table 1 presents the summary of mean fuel consumption of various
category of vehicle in different cities. The mean fuel consumption observed for each category
of vehicle in the hot stabilised condition, which is based on the measured fuel consumption
for each of the three run for 10 minutes duration is presented in the Table 1. Four wheeler
petrol powered vehicles tested included technology such as carburettor as well as multi point
fuel injection. The two wheelers tested were motorcycles using the 4 stroke cycle technology.
The three wheeler tested were all petrol powered using 2 stroke cycle technology and having
the same engine capacity from the same vehicle manufacturer. Total of 143sample of four
wheelers, 20 number of three wheeler and 122 two wheelers were testes at various cities. The
idling fuel consumption for four wheelers, three wheelers and two wheelers were observed to
be 97.98 ml, 40 ml and 23,83 ml respectively over 10 minutes duration. The variation in fuel
consumption among different cities for the same vehicle type could be due to differences in
vehicle technology, maintenance practices, fuel quality, emission regulation enforcement
followed etc.
Table 1 Summary of Mean Fuel Consumption of Petrol Vehicles tested at Idling
Sr. No.
Vehicle category
No. of
vehicles
Tested
Mean fuel
consumption
(ml/10 min)
Name of the City
1
Four wheeler
30
99.5
Bhopal
49
88.0
Chandigarh
18
107.3
Pune
13
112.8
Chennai
4
81.7
Kolkata
29
98.6
Delhi
2
Three wheeler
20
40.0
Bhopal
3
Two wheeler
26
26.9
Bhopal
22
25.3
Chandigarh
11
22.3
Pune
28
22.8
Chennai
19
21.2
Vadodara
5
27.6
Kolkata
11
20.7
Delhi

3.2 Fuel Consumption of Diesel Vehicles at Idling
A total of 61 Diesel vehicles includes four wheeler, Bus, Light and heavy duty trucks were
tested at different cities. Table 2 presents the summary of mean fuel consumption of various
category of vehicle in different cities. The mean fuel consumption observed for each category
of vehicle in the hot stabilised condition, which is based on the measured fuel consumption
for each of the three run for 10 minutes duration is presented in the Table 2.. The Light Duty
Truck and Light duty Bus tested were both powered by Diesel engine. The idling fuel
consumption for four wheeler, Bus and medium truck is 97.8, 154 and 167 ml/10 respectively.
The variation in fuel consumption among different cities could be due to differences in engine
capacity, vehicle technology, fuel quality etc.
Table 2 Summary of Mean Fuel Consumption of Diesel Vehicles tested in Idling
Sr. No.
Vehicle
category
No. of
vehicles
Tested
Mean fuel
consumption (ml/10
min)
City
1
Four wheeler
6
107.6
Bhopal
5
96.5
Chandigarh
1
82.2
Pune
4
84.2
Chennai
7
100.0
Kolkata
3
116.3
Delhi
2
Bus
2
141.0
Bhopal
1
170.4
Chandigarh
13
153.1
Vadodara
3
Light duty
Truck
4
88.3
Bhopal
4
Light duty Bus
11
108.2
Bhopal
5
Truck
1
419.3
Chandigarh
1
120.9
Chennai
6
Medium Truck
1
167.0
Delhi
7
Mini Truck
1
103.5
Delhi
4. DATA ANALYSIS
Out of the 348 vehicles tested in all the identified cities It was observed that motorcycles and
Four wheeler Petrol driven vehicles are tested in dominant proportion. The number of diesel
vehicles tested is in a very small proportion. It is further observed that three wheeler were
tested only in city of Bhopal. Mini Bus and Mini Truck used the same engine in Bhopal.
Motorcycle around 100 cc engine capacity was tested in considerable number among two
wheeler vehicle category, similarly 800 cc engine capacity petrol powered four wheeler was
tested in considerable number among the four wheeler petrol powered vehicle category. The
maximum engine capacity of four wheeler petrol powered vehicle which were tested was

observed to be 1800 cc, which is Ambassador Car. To understand the correlation of fuel
consumption and engine capacity in petrol powered vehicle. Data of measured fuel
consumption was combined from all the cities to get sufficient number of data points and the
vehicle were categorised as per class interval for engine capacity as follows
 Engine capacity up to 800 cc
 Engine capacity from 800 cc up to 1000 cc
 Engine capacity from 1000 cc up to 1100 cc
 Engine capacity from 1100 cc up to 1200 cc.
 Vehicle beyond engine capacity 1200cc.
Similarly for motorcycles, the vehicles were categorised as per class interval for engine
capacity as follows
 Engine capacity up to 100 cc
 Engine from 100 cc up to 110 cc
 Engine capacity from 110 cc up to 125 cc
 Engine capacity from 125 cc up to 150 cc.
 Engine capacity beyond 150 cc was ignored.
Four wheeler diesel driven vehicle had engine capacity from 1400 cc up to 3000 cc, all these
data were combined together to understand the effect of engine capacity on fuel consumption.
The tested vehicles were observed for the engine technology and categorised into the
following vehicle type to understand fuel consumption by combining data of fuel
consumption of all vehicle types from different cities and shown in Table 8. Data of perceived
vehicles mileages by vehicle users is shown in column 7 in Table 8. It gives an idea that 10
minutes of idling is equivalent to at least one kilometre of travel for light vehicles.
Table 8: Statistical Summary of Fuel Consumption of vehicles tested at Idling
Sr No.
Vehicle type
Vehicle
technology
FC (ml/10 min.)
Sample size
Perceived
Vehicle
Mileage by
Vehicle
Users
(kmpl)
Mean
Std. dev.
1
Motorcycle
4 stroke
24
8
121
55
2
Three wheeler
2 stroke
40
12
20
25
3
Car (Petrol)
MPFI
90
13
113
12
4
Car (Diesel)
Direct Injection
94
18
6
10
5
Car (Diesel)
Indirect Injection
103
19
16
14
6
Car (Petrol)
Carburettor
124
37
30
12
7
LCV(Diesel)
Direct Injection
113
31
19
6
8
BUS(Diesel)
Direct Injection
150
29
15
4

Fig 7: Fuel consumption of different category of vehicles
The mean value of observed fuel consumption at idling is predominantly dependent on engine
capacity and vehicle technology and varies from 144 ml/hr to 900 ml/hr for the observed
vehicles tested in different vehicle categories across different cities. There is a huge variation
in fuel consumption of vehicles across different cities under same vehicle category. Further,
the vehicles which are more than 10 years old showed a distinct increase in fuel consumption
among four wheelers and bus (Fig 8).
Fig 8 Idling Fuel consumption of vehicles for different model year
5. SIGNIFICANT FINDINGS
The mean value of observed fuel consumption at idling is predominantly dependent on engine
capacity and vehicle technology and varies from 144 ml/hr to 900 ml/hr for the observed
vehicles tested in different vehicle categories across different cities. There is a huge variation
in fuel consumption of vehicles across different cities under same vehicle category. Further,
the vehicles which are more than 10 years old showed a distinct increase in fuel consumption
among four wheelers and bus (Fig 8). Both vehicle technology and vehicle mileage contribute
to significant variation in fuel consumption at idling. Lower fuel consumption at idling due to

improved vehicle technology as well as traffic control measures will translate into significant
improvement in air quality.
6. REFERENCES
Amanda, R, Carrico., Paul, Padgett., Michael, P, Vandenbergh., Jonathan, Gilligan.,
Kenneth, A,Wallston.(2009) “Costly myths: An analysis of idling beliefs and
behaviour in personal motor vehicles” Energy policy, 37, 2881-2888.
Burke, R.D., Brace, C.J., Hawley, J.G.,(2011) “Critical evaluation of on-engine fuel
consumption measurement. Proceedings of the institute of Mechanical Engineers”,
Part D:Journal of Automobile Engineering, 223(6),pp 829-844, ISSN 0954-4070.
Francisco, Posada., John, German.,(2013) “Measuring in-use fuel economy in Europe
and the US: Summary of pilot studies”. Working paper,5, International council on
clean transportation.
Vilnis, Pirs., Zanis, Jesko., Janis, Lacekiis-Bertmanis.,(2008). “Determination methods of
fuel consumption in laboratory conditions”. Engineering for Rural development,
Jelgava, 05,29-30,05.
Zhang, Xiao., Zhao, Dui-Jia., Shen, Jun-Min.,(2012) “A synthesis of Methodologies and
Practices for Developing Driving cycles”. Energy Procedia, 16,1868-1873.