How did car become the instance in the sets and gets $?$

#include

#include

using namespace std;

$//$ Define Class MPG

class MPG $\{$

$//$ Declare the Private Members

private:

double miles, gallons;

$//$ Declare the Public Members

public:

$//$ setMiles$()$ method, sets the Miles

void setMiles$($double mile$)$

$\{$

miles $=$ mile;

$\}$

$//$ setGallons$()$ method, sets the Gallons

void setGallons$($double gallon$)$

$\{$

gallons $=$ gallon;

$\}$

$//$ getMiles$()$ method, returns the value of Miles

double getMiles$()$

$\{$

return miles;

$\}$

$//$ getGallons$()$ method, returns the value of Gallons

double getGallons$()$

$\{$

return gallons;

$\}$

$//$ getMPG$()$ method, returns the MPG

double getMPG$()$

$\{$

return miles $/$ gallons;

$\}$

$\}$;

$//$ Main$()$ Function

int main$()$

$\{$

$//$ Declare the variables

double mile, gallon;

$//$ Create an Instance of MPG

MPG car;

$//$ Input the No$.$ of Miles

cout Enter Number of Miles: $"$;

cin $>>$ mile;

$//$ Set the Miles using setMiles$()$

car.setMiles$($mile$)$;

$//$ Input the No$.$ of Gallons

cout Enter Number of Gallons: $"$;

cin $>>$ gallon;

$//$ Set the Gallons using setGallons$()$

car.setGallons$($gallon$)$;

$//$ Get the MPG using getMPG$()$ method. To print only $2$ decimals, use setprecision$()$ and fixed.

cout Miles per Gallon: $"$ fixed $$ setprecision$(2)$ car.getMPG$()$;

return $0$;

$\}$nstance for the MPGmain $??$