1% is 1%
I'd add it.
I'm adding 3.4% due to larger tyres, but I really should check the odometer against GPS / kilometre signposts.
In my experience though,
speed is always overreported
(as legally they may not show you're going slower than you actually are)
odometer OTOH is quite correct
In the up! , the speedo even shows a different speed than the digital speed readout buried in the OBC !
Speedo indicates highest.
OBC reports a few kph less than speedo.
GPS reports yet another few kph less than OBC ...
And that's even despite the tires being too large!