Car modelling without blueprints?

Has anyone ever modelled a car/vehicle without blueprints? How hard is it ?

If you’ve got several reference photographs of the thing it’s manageable, especially if you’ve got a front-on or a side-on shot. It’s really important to get the scale of the various pieces believable in relation to each other. It may sound a bit strange to suggest that you go “take a tape-measure to a real car,” but it’s worth doing.

Thanks for replying, How accurate is the model of the car using ref photographs only compared to a car made following Blueprints ?