In Model Based Testing (MBT), test cases are generated automatically from a partial representation of expected behaviour of the System Under Test (SUT) (i.e., the model). For most industrial systems, it is impossible to generate all the possible test cases from the model. The test engineer recourse to generation algorithms that maximize a given coverage criterion, a metric indicating the percentage of possible behaviours of the SUT covered by the test cases. Our previous work redefined classical Transition Systems (TSs) criteria for SPLs, using Featured Transition Systems (FTSs), a mathematical structure to compactly represent the behaviour of a SPL, as model for test case generation. In this paper, we provide one all-states coverage driven generation algorithm and discuss its scalability and efficiency with respect to random generation. All-states and random generation are compared on fault-seeded FTSs.