What is the OBDII Car MPG Demo (Gasoline) application, how does it work?

According to the introduction of CHINH LUONG QUOC, OBDII Car MPG Demo (Gasoline) is a Tools app on the Android platform. There is currently a 1.1.3 version released on Jul 15, 2019, you can see the details below.

Version 1.1.3
Tool for every car (Gasoline or Gasohol engine)
Runs on Android Mobile and Tablet devices


Requirement:
1. The car must be OBD-II compliant to use the tool
2. A Bluetooth Adapter ELM327 or compatible
3. The minimum Android OS is : 4.1 and newer
4. The built-in bluetooth device on the phone(Tablet) must be enabled and paired with the bluetooth OBD-II adapter

OBD-|| protocol:
* The functionality of Auto detect the OBD-II protocol let's the app to be very easy to use
* Displaying the description of the protocol used in the car
SAE J1850 PWM (Ford)
SAE J1850 VPW (GM)
ISO 9141-2 (Chrysler, European, Asian)
ISO 14320 KWP-2000
ISO CAN 15765 - 11bit, 29 bit, 250Kbaud, 500Kbaud (most models after 2008)

Features:
* The MAF or MAP, IAT (OBDII PIDs) must be supported by the car
* Fuel consumption can be calculated, if a vehicle supports Pid 0x0D Vehicle Speed (Vss) and Pid 0x10 Mass Air Flow (MAF). All vehicles support vehicle speed and nearly all vehicles support MAF.
* As for other ways of doing this, especially if your car does not have a MAFsensor, by knowing the displacement of the engine (ED), and the "volumetric efficiency" (VE) of the engine, MAF can be calculated from RPM, MAP and IAT. With VE, one can use the following formulas to calculate a synthetic "mass air-flow" (MAF) in grams per second , all without a MAF sensor, using the "Ideal Gas Law", as follows:

IMAP = RPM * MAP / IAT
MAF = (IMAP/120)*(VE/100)*(ED)*(MM)/(R)

Notice:
* The DEMO version shows example and detects that if your car supports MAF pid or MAP pid, or you can not use this app for your car.

New feature on the Pro version:
* Use SqLite database for data storage .
* Feature Review your route on Google Map with data of MPG(OBDII), speed(OBDII), time and GPS.The app will store data into SQLite database and then can review on Google map. The data stored in database is the integration between GPS location data and OBDII data together

Use with real car :

Once you have the bluetooth OBD-II adapter plugged into the car's OBD-II ports and powered on, you need to connect to the car's system computer via that bluetooth adapter, by pulling down the option menu and select item "Connect to OBD-II Adapter", a dialog window will appears and shows a list of paired devices (one or more devices in the list), each paired device has two information as following:
Name of paired bluetooth device (for example: obdii)
Max address (for example: 77:A6:43:E4:67:F2)
The Max address is used to distinguish two or more bluetooth adapters have the same name.
You must choose your bluetooth OBDII device by select the correct it's name (or it's max address) in the list and click on the item, then the app starts connecting process and autodetects the OBD-II protocol.

Use with "ECU Engine Pro" app from Google Play Store (Simulation only):

The "ECU Engine Pro" app is installed into an other device and act as a car engine ECU simulation. The connection to this device is the same as above with a real car

Screen arrangement
* 4 small analog gauge for IAT, MAF, MAP, VSS, RPM realtime data reading, 1 big analog gauge for showing instant MPG value and a table used to display the average (AVG) MPG, L/100Km, amount fuel consumed in Gallons and in liters
* 2 Odometers calculated in Miles and in Kilometers. 1 tripmeter for time since engine start
* A logo indicates Fuel type (Gasoline or Exx) , a logo indicate either US Gallon or Imperial (UK) Gallon

Setting...
For example the VE of 1999 7.4L Chevy Suburban is about 65%. Smaller, higher performance engines can have VE's of 85% or higher. (By convention : We set VE = 0.65 for 65% ...)
The ED we set ED = 1.6 for engine 1.6 liters ...
Set the Fuel type as Gasoline or Exx , set Gallon US or Gallon UK

The result of last work is stored and will be reloaded for next time you run the app. these data will be overwritten automatically when the app stops (finish)