In reply to hughsaints:
2 cars is by far the better option.
But if you have no choice it would be doable, but maybe cache some food and water near descent. Not sure if there's a path under the ridge, but if there is it will likely be rough, steep, loose, and spiky! Unless you do a recce beforehand i'd stick with the road walk back. It's long (a few km's, not sure exactly how many) and could easy take +1.5 / 2 hours.
If you're after a good quality ridge day and only have the 1 vehicle, have a look at some of these as alternatives, all apart from El Realet require only 1 vehicle:
http://www.mountain-journeys.co.uk/ridge-traverses--easy-climbs.html
Hope that's of some help.
Mark