The ad shows a picture of an attractive young woman wearing only a bra and advises women that the "other way to a man's heart" is by visiting the British Motor Show, which is full of "boys' toys".
The Advertising Standards Authority described the ad as "tasteless", but decided that it was unlikely to cause widespread offence and did not make an adjudication on the ad.
Hewitt had criticised the ad to a group of reporters over the weekend, but yesterday appeared on GMTV repeating her comments. She said: "This is out of date and it is going against what the individual carmakers themselves are saying, which is that half their potential consumers are women."
The organisers of the show claimed that the poster was designed for women by a woman, and said it was "witty".
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