Ninety per cent of a comedian's working life is spent not on stage, but in car travelling to or from gigs.

What's more they're usually shared journeys, and when you get two or more stand-ups together they're guaranteed to engage in a comedic pissing competition, to see who can outfunny the others.

Kevin Shepherd's brilliant idea was to film all these conversations and edit them into an Edinburgh show. This way he's got more that a dozen comics, writing his show for him.

Most of them are from the lower end of the professional comedy ladder where ride-sharing is a financial necessity, but you also get rather incongruously, Jimmy Carr mulling over the finer points of a stand-up's life.

Every would-be comic should watch this show to get an idea of the sort of conversations you can expect on that seven-hour drive to Plymouth, with at least most of the tedium and vacuous banter exorcised.

But what of those with only a passing interest in comedy? Paul Provenza's film The Aristocrats proved there's a market for documentaries on an unseen sides of the comedians' art, and there are certainly enough jokes in this to keep today's non-partisan audience laughing.

Shepherd hasn't, perhaps, shot quite enough footage to edit from, with certain sequences are a bit too much like in-jokes on the particular comics. Australian Pam Ford, for instance, is edited to make her out to be constantly talking about her boyfriend, as if anyone really cares.

If Big Brother has taught us one thing, though, it's that people do care about the inanities of strangers' lives, and Comics Die In Hot Cars is not such a great leap from reality TV, only with the advantage that it features people who do have some comic sensibilities. And , in a neat gimmick, one of them appears live in the show each day to do five minutes of their material - tonight it was Carl Donnelly.

Shepherd's on-stage contribution in introducing the clips is minimal ­ genial enough but hardly comedy dynamite. But then he has already contributed the idea in the first place ­ and what a good idea it turned out to be. Enjoy the ride.

Steve Bennett