With the next available row as the starting point, this will loop through each of the Models on SheetB and produce the distinct Model: Year combinations. As a result, if SheetB already has some data, this macro will add values underneath it rather than overwriting it.
Sub mydearmacro()
Dim a_ws As Worksheet: Set a_ws = ThisWorkbook.Sheets("SheetA")
Dim ws As Worksheet: Set ws = ThisWorkbook.Sheets("SheetB")
Dim a_lr As Long, lr As Long
a_lr = a_ws.Range("A" & a_ws.Rows.Count).End(xlUp).Row
Dim model As String
Dim i As Long, y As Long, x As Long
For i = 2 To a_lr
model = a_ws.Range("A" & i).Value
start_year = a_ws.Range("B" & i) - 1
y = a_ws.Range("C" & i) - a_ws.Range("B" & i) + 1
lr = ws.Range("A" & ws.Rows.Count).End(xlUp).Row
For x = 1 To y
ws.Range("A" & lr + x).Value = model
ws.Range("B" & lr + x).Value = start_year + x
Next x
Next i
End Sub