No such thing as comparative data
Almost everything you see is a fiddle in some way.
One firm quotes IAS. Another quotes TAS at 10000ft. Another (with a turbo) quotes TAS at 25000ft (omitting the small detail that the endurance of the oxygen system at 25k will be considerably less than that of the fuel tanks).
Then you get onto range. Even more permutations there. Some are zero reserve, some (usually N-reg) will be with legal IFR reserves. Then you get range at different power settings. Most planes will deliver best range at slightly over Vy (best range is actually
at Vy but the engine isn't efficient at such a low power) but nobody will want to fly that slowly.
Operating ceiling is another one. It can be defined at different climb rates.
Some of it one can work out backwards (using common "universal" corrections) to arrive at comparable figures, but the basis for a lot of it remains a mystery.
And a plane whose engine is operated lean of peak will beat another run as per the POH by a good margin. Amazing to see an old bent-metal machine beat a modern composite one when doing this.