You should get your code formatting and indentation right so you'd see what line of code belongs where. This way you could easier match the Begins and Ends, etc.
I've fixed up the code for you:
program CarShow;
Var
CarModel : string;
CarCounter1, CarCounter2, CarCounter3 : integer;
RentalFee, TotalRentalFee1, TotalRentalFee2, TotalRentalFee3 : real;
Const
RentalFee1 = 1500;
RentalFee2 = 2000;
RentalFee3 = 2500;
Begin
CarCounter1 := 0;
CarCounter2 := 0;
CarCounter3 := 0;
TotalRentalFee1 := 0;
TotalRentalFee2 := 0;
TotalRentalFee3 := 0;
RentalFee := 0;
writeln ('Please enter the model of car.');
readln (CarModel);
If (CarModel = 'Kia Celtos') Then
Begin
RentalFee := RentalFee1;
CarCounter1 := CarCounter1 + 1;
TotalRentalFee1 := TotalRentalFee1+RentalFee;
End
Else If (CarModel = 'Kia Sonet') Then
Begin
RentalFee := RentalFee2;
CarCounter2 := CarCounter2 + 1;
TotalRentalFee2 := TotalRentalFee2 + RentalFee;
End
Else If (CarModel = 'Kia Forte') Then
Begin
RentalFee := RentalFee3;
CarCounter3 := CarCounter3 + 1;
TotalRentalFee3 := TotalRentalFee3+RentalFee;
End
Else
Begin
Writeln ('Sorry incorrect entry')
End
End.