A handful of months ago I read up on various aero gravel bikes, I think it was after listening to a NerdAlert podcast that referenced a new offering that claims to be aero and offered no data to back it up.
I struggled to find actual data to show X is faster than Y. I did see claims that a new model is faster than the old model, that general comment was pretty common.
Scott Addict Gravel
Ridley Kanzo Fast
Cervelo Aspero
3T Exploro
Open Upper
BMC URS
Specialized Crux
These were commonly listed and I dont remember seeing wind data or anything like that for any of them. It was more commentary like 'Scott borrowed these 4 design elements from their aero road bike when designing the Addict Gravel'. To me, that means no actual testing was done and it was just simulation during design. I think when actual testing is done, they proudly feature the results.
...just dont tie a number to the front of the bike or hang a bar bag and totally ruin the aero gains.