How do I display the speed limit on Google Maps in iOS?
According to Google's Product Forums, they're doing limited speed limit display tests in very specific areas.  I've seen San Francisco and Brazil being listed as the only places it's available right now.

They're also A/B testing in other locations.  No official release date has been given by Google for when this will be available on iOS.

To do a feature request:


Open Google Maps and make sure you’re signed in.
In the top left, click the Menu .
Tap 'Help &amp; Feedback'.
Select 'Send Feedback'
Tap 'Send app feedback'
Click Send.