People today misunderstand why women are so prominently featured in old car ads.
Until electronic ignitions came along a cold engine could be hard to start. a concenient way of avoiding starting problems was for a girl to sit on the hood and use her subcutaneous fat layer to keep the engine from cooling.
![](http://i37.servimg.com/u/f37/17/91/41/66/94202610.jpg)
Etymologists agree this practise was the origin for the phrase "hot" girl: a girl who could well keep a motor warm.