be economical with the truth -> δεν είμαι απολύτως ειλικρινής, αποκρύπτω την αλήθεια, είμαι φειδωλός με την αλήθεια, δεν τα λέω όλα, κρατάω και κάτι, είμαι σφίγγα
to not be completely honest about something
He was economical with the truth - he gave her a censored account of what was discussed.http://idioms.thefreedictionary.com/be+economical+with+the+truth