As always, the police warn of the dangers they face: stagger your departure, they will say, stop for a rest every two hours, don't drink alcohol and, above all, avoid the A6, the "motorway to the sun", which is the city's high-speed, high-risk conduit to the Midi, except when it is jammed.
The authorities have done their best to encourage other routes: they signpost myriad alternatives along France's equivalent of A roads, they have completed a motorway out of Paris to the south-east, the A5 and they plan a similar road to the south-west. A motorway due south, the A75, is also finished bar the last stretch from the Cevennes to the sea.
Yet Parisians stubbornly prefer the A6 and I have a confession: I do too. It is not just straighter and wider than the alternatives but it supplies a constant revelation of the geography and regional diversity of France, offering an ever-changing backdrop that speeds the transition from butter-eating north to the olive- oil-drenched south and back again.
No sooner have you tired of the environs of Paris, its hypermarkets, suburban estates and low-flying planes from Orly, than you are approaching the dark layered forest of Fontainebleau. As the forest grows sparse, you are already skirting the Chablis and entering the woods and fields of Burgundy, where billboards proudly illustrate the white Charollais beef cows that graze peaceably in the meadows.
From the higher ground of Burgundy a panorama opens out of the Morvan, a wild landscape of pastel colours and fierce weather. Past the mediaeval market centre of Auxerre, the holy city and pilgrimage centre of Vezelay appears on the signposts. The forests are now fir: this is where Parisians get their Christmas trees.
Once the turning to Dijon, mellow stone capital of the Burgundian dukes is past, the houses are sleeker and lower. Slate roofs give way to red tiles, hay and kale to vines. The rounded hills of Beaujolais rise to the west and the signs suggest a vintner's catalogue: Macon, Fleurie, Julienas ...
Almost before you have time to overtake another lorry, you are on the threshold of Lyons, capital of Roman Gaul. Here, Parisians distinguish themselves for the second time.
Having chosen the A6, they scorn the recent relief motorway, a long loop that seems to veer more to Geneva than the Midi, and brave instead the tunnels that run beneath the city centre and emerge across the blue-grey Rhone. So what, if we are caught in a jam? You feel you are passing a great city and heading ever south.
From Lyons, the Rhone is always alongside; the names on the signboards are already lyrical, evoking the delights of the Midi: Vienne, Valence, Montelimar, Orange and finally Avignon, city of the popes. The vines sweep to the road; the pines are of the Mediterranean umbrella variety, the stone is golden and the roofs are tiled.
Before Avignon, the motorway divides, and so do France's sun-seekers: to the east are the traditional and highly concentrated holiday grounds of the Cote d'Azur; to the right, the quieter, more rustic resorts of Languedoc-Roussillon, and the road to Spain.
Perhaps it is the distractions, perhaps a sense of purposeful solidarity that the A6 fosters, but the driving rarely seems as aggressive or harebrained as on the "N" roads. French lorries seem more patient, French cars fast, but generally civil. Trouble, if it comes, invariably originates with a Spanish or Belgian number plate.
And the A6 seems to appreciate its Parisians. To those reaching the end of their journey north, it offers a small white sign with a line drawing of the Eiffel Tower and "50km" marked underneath. "Welcome back, Parisians," it is saying in a reserved French way, "you're nearly home."