Hi, I’ve noticed this while flying particular larger jets like 747 or a380. the speed autopilot doesnt really gets me to that speed. its always 0.01-0.02 mach number slower. if i’ve set speed to mach 0.85. it’ll fly at mach 0.83. and it is not that it can’t accelerate further. i see the throttle at 80%. if i turn off autopilot. accelerate manually. then engage autopilot it again slows my speed down.
also with 747 auto pilod. during climb it breaks my vertical speed a lot early than my set cruise altitude. it climbs the last 500 feet at about 100-200 feet per minute.