I have not flown FSX since getting back into Aces High in May, but to answer your question.
A2A simulations produce the most realistic aircraft for FSX. They have both civilian and military aircraft. Their Cessna 172 would be just what you are looking for. They also offer the piper Piper Cherokee and other civilian rides. Military rides include P5i, P47, P40, AT6 Texan and B17 among many others.
These have highly realistic flight models and engine management. Check out "a2asimulations.com" and many youtube videos of their aircraft. You won't be disappointed.