Originally posted by uechtel
Already in 1939 there had been a Kronstadt GP which had been won by Dr. Fritz Werneck in the 1.5 litre class (BMW 315/1). He joined the caravan, too, to be there also in 1940. BMW had intended von Hanstein, Briem and Bäumer as their drivers... They were accompanied by Ernst Loof in a BMW 321 with a 328 engine. The team - some of the men were soldiers and were on extra holidays - had intended to stay a little longer in Romania to take poart also in the Romanian GP which was scheduled a week later.
WHEN PRACTISE AT KRONSTADT WAS IN FULL GOING came the signal for retirement. Hungarian troops had invaded Romania and so also this part of Europe had been grasped by the war. It lasted some concerning weeks until the convoi of racecars returned at home safely..."
From Bartleby.com:
Aug. 30 Under pressure from Berlin and Rome, the government agreed to yield an area of 16,642 square miles with a population of almost 2.4 million to Hungary (Vienna conference).
Sept. 6 Under pressure from the Iron Guard, King Carol fled and was replaced by his son, Michael.
Sept. 8 A further territorial cession of some 3,000 square miles (southern Dobrudja) was demanded by, and yielded to, Bulgaria (Treaty of Craiova).
Oct. 8 German troops entered Romania to “protect” the oil fields.
No mention of a Hungarian "invasion"

, but presumably they moved into their new lands quite quickly.
My guess for the dates of the two races would therefore be September 1st (Kronstadt GP) and 8th (Romanian GP). BUT the Italian GP had originally been scheduled for the 8th too, so who knows? Perhaps AU had already set transport aside to get to Italy and decided to use it to go to Romania instead?
In the WW2 Racing thread, Tony Kaye posted a date for the Feleac hillclimb in 1940, which was to take place on October 6th.