My speed on my garmin edge 510 is displaying what I feel on the open road when doing 30km/h but the speed in Zwift is vastly higher than this number (5-10km/s more on flat) which at the end of a ride will accumulate to “fake” Kilometers traveled and this is not very desireable data to upload to my strava account 
Could you please add a feature to decrease the speed that I am traveling at in zwift so that I stop accumulating Miles that I have not traveled.
correction and clarifications: The speed is in KM/h obviously and the setup that I am using is cycleops fluid 2.0. When Im getting a resistance on the pedals of what I feel like when doing 30km/h in the open world , the speed displayed in Zwift is much higher.
The thing is that the garmin edge 510 displays what the actual speed really feels like so this tells me that my trainer is really well calibrated and realistic to real wolrd conditions but on the other side you got zwift who thinks the fluid 2.0 has a greater resistance curve that what it really is.
The speed outside and indoors will never be identical. There are simply too many variables involved.
Zwift uses a power curve for each classic trainer and depending on the make and model, the power curve may be more accurate than others. The most accurate measure will require a power meter. In any case, we take into account the watts (estimated for classic trainers), your weight, your height (to determine body mass and therefore air drag), your bike, your wheels and the terrain on Zwift to determine your speed in the game. This will never be identical to the real world. What matters more than anything else is that your set up produces consistent results.
Hope this helps!
You’re actually concerned about a “fake” reading on “miles travelled” on a static trainer compared to riding on the road?
PMSLROFL
There’s only one number you need to know about actual miles travelled on a turbo trainer. That number is a big fat zero. 
As Eric says, "This will never be identical to the real world."
Other features will never be identical to the real world.
But one thing is identical to the real world, it’s when you suffer trying to follow a rider who is faster than you.
That’s the most important acording to me.
I think there is simple solution: transmission virtual speed from Zwift. If this feature will be implemented, one can connect it to cycle computer (like Edge) as speed sensor.
Transmission of ANT+ signals to be picked up by a computer is technically quite feasible, but not sure why you need it as your speed is shown in the game and on the smartphone app.
Mark,
Cycle computers like Garmin Edge can provide many metrics that not available in Zwift app: avg, max, segment speed/cad/power/hrm, IF, NP, TSS etc.
Transmission of power is useful for zPower users.
Sometimes i’d like to hide Zwift HUD and concentrate on effort, enjoy ocean view and rarely look at my Garmin.
Go to ~/Documents/Zwift/prefs.xml
Between the <CONFIG> and </CONFIG> tags add this line:
<MINIMAL_UI>1</MINIMAL_UI>
There you are, no more Zwift HUD or any other laid over graphics at all.
Mark,
It works, thank you! I wish there was a hotkey for this.