Please add your own to the list.
Currently the 109s have the following issues:
- auto prop pitch bug on the E-4. It needs to be switched on, tempered with in manual, and then switch back to actually work
- None of them can reach historical level speeds and is slower by ca. 40 km/h
- altitude FM bug (common to all planes)
- pilot/fuel tank armored bulkhead is not modelled
- stall modelling, with unpredictable and violent stalls, flat spins
- it overheat model is much worse than the real thing, which could sustain allowable temperatures at 1/4 radiator open (or 3/4 closed) in level flight
- the weight of E-1, E-3, E-4 is slightly off (though I do not think this is that much of an issue, since turn times are hard coded and it should only effect behaviour)
- ground handling model is simplistic (common to all planes)
- best climbing speed is off, it's 270 km/h instead of 250 kph, which may seem unimportant, but it has an effect on the turn/climb envelope, curve and related tactics, low speed flight etc.
- tail wheel lock is present in 3d cocpit model (it was present on E-7 onwards)
- speaking of which there's no E-7
- no E-4/N either :p
- manual prop pitch lacks feathering option (historically setting the level to the lowest position set the airscrew to be feathered)
- armament signal lights are wrong in cocpit