The details of the plane (Bf 109 G-1 Endzustand) used for those calculations are shown in sheet IV/31/42. It includes the following improvements over the standard calculated performance of G-1:
There is your explanation, Gripen. I have FW-190 flight-tested performance that gives 700kph at 2nd Gear FTH. The same aircraft is also much slower at sea level.
Hardly typical but well within manufacturers guarantee.
For what it is worth:
German flight testing procedures tend to follow a different format than the allied ones for standard production performance in my experience. While the allies tend to test one or two aircraft producing a report specific to that serial number, the Germans tended to test multiple aircraft over several hundred flights. This can be seen in the Me-262 report posted in this thread.
They then produce a general report describing the average performance and specific aircraft set up used. Mtt will publish calculated figures included in this report as well many times. Focke Wulf does not usually include calculations in the report. A flying schedule and list of pilots and aircraft flown can sometimes be found as an appendix or referenced as a separate report in the case of Focke Wulf, Gmbh.
Focke Wulf produces the calculation reports separately from the flight test as well. These calculations tend to be extremely detailed and all the reports I have for FW-190V5g thru FW-190D15 are several hundred pages of calculations. For example the calculation report for the FW-190A8 are over 500 pages. Calculations are also very distinctly labeled as such.
Mtt will almost always include general calculation sheets as well in flight test reports:
http://www.beim-zeugmeister.de/zeugmeister/index.php?id=28&L=1As a general trend, calculations tend to be conservative and not optimistic in any aircraft manufacturer. It is just simple economics. Everyone comes out a winner with conservative estimates and everyone looses with optimistic ones.
All the best,
Crumpp