ℛcar=ReliabilityDistribution[wheels∧engine∧transmission∧(brake1∨brake2),{{wheels,ExponentialDistribution[(Subscript[λ, 1])]},{engine,WeibullDistribution[a1,b1]},{transmission,ExponentialDistribution[(Subscript[λ, 2])]},{brake1,ExponentialDistribution[(Subscript[λ, 3])]},{brake2,ExponentialDistribution[(Subscript[λ, 3])]}}];

SurvivalFunction[ℛcar,t]

vals={(Subscript[λ, 1])->(1/5),(Subscript[λ, 2])->(1/10),(Subscript[λ, 3])->(1/15),a1->5,b1->12};

mttf=NExpectation[t,t\[Distributed]ℛcar/.vals]

ListPlot[{RandomVariate[ℛcar/.vals,100],{{0,mttf},{100,mttf}}},Joined->{False,True},Filling->Axis,AxesOrigin->{0,0}]