I have read about the 750 cc engine size too, e. g. in Georgano's Encyclopedia of Commercial Vehicles. But according to René Bellu, Claveau featured two engines for its car range in 1930: the 9 CV 1500 cc flat-four four-stroke and the 4 CV two-cylinder two-stroke with bore and stroke of 70 x 75 mm which results in a 570 cc displacement (577 cc to be mathematically correct). Do you have a contemporarry proof for the 750 cc engine size? Otherwise I would suppose that some book author involuntarily flipped the digits to the much more usual 750 instead of 570.
BTW, Claveau used the same drawing for their 6 CV model of 1932. Just the door opening has been enlarged and the lettering at the side has been altered.
