I have rented a few times with Sixt US but at their LAX station so YMMV: the two times I got the X5 xDrive40i, (was at 2022 and 2023) both did not have active cruise control (and also did not have the adjustable air suspension which I thought were standard for X5 in the US, but oh well). One time I rented an X3 (December 2022) also at LAX it didn't have active cruise control either. But I rented the i4 eDrive40 last December and it did have active cruise control (actually it could also change lanes for you), which was a nice surprise.