@ lee1971
you must enable it from gp4tweak.ini and from gp4tweak_data.ini you can select which cars you want to remove like this one ( I have removed Arrows team):
Set cars that availables per track/circuit
; Value is in bool; 1 = available, 0 = not available
; aliases -------------------------------------------------------------------
; Enge -+
; Frentzen - + |
; Young - + | |
; Alonso - + | | |
; De La Rossa -+ | | | |
; Irvine - + | | | | |
; Raikkonen -+ | | | | | |
; Heidfeld -+ | | | | | | |
; Bernoldi -+ | | | | | | | |
; Verstappen -+ | | | | | | | | |
; Trulli -+ | | | | | | | | | |
; Alesi -+ | | | | | | | | | | |
; Panis -+ | | | | | | | | | | | |
; Villeneuve -+ | | | | | | | | | | | | |
; Button -+ | | | | | | | | | | | | | |
; Fisichella -+ | | | | | | | | | | | | | | |
; Montoya -+ | | | | | | | | | | | | | | | |
; R Schumacher -+ | | | | | | | | | | | | | | | | |
; Coulthard -+ | | | | | | | | | | | | | | | | | |
; Hakkinen -+ | | | | | | | | | | | | | | | | | | |
; Barrichello -+ | | | | | | | | | | | | | | | | | | | |
; M Schumacher -+ | | | | | | | | | | | | | | | | | | | | |
; | | | | | | | | | | | | | | | | | | | | | |
Melbourne = 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1