Yes I'm adding my vote to this request. Fuel Light/Reserve is very good idea.
Optical (Light on tachometer/dashboard) and acoustical (PIP sound) signaling if the Reserve Tank/Fuel reached. When fuel reach the Reserve level in tank, then it should be signaling by optical light and acoustical PIP sound in dashboard. This signaling (light and PIP) should be activated at every new starting of engine, when fuel is on reserve - as in real car. For more flexibility if you want, it can be configured by user. Level of reserve tank may be configured by user (% or liters), and this signaling can be turned ON or OFF button by user in LFS configuration menu. Existing of this Reserve Tank/Fuel signalling is very requested, but possibility of modification or configuration of reserve level not must be existing. It can be programmed on fix value as in real car (can not be modified the reserve level). Each car may have his own reserve level tank (threshold level for signalling of reserve tank). Users who want this Reserve Tank signaling, they can turn ON this feature, and users who don't want this, they can turn OFF this signaling.