It’s the perfect dish. Just perfect. I’m on the fourth course of chef Yoric Tièche’s divine ocean-themed tasting menu – served with a wash of balmy Mediterranean air on the terrace of the Grand-Hôtel du Cap-Ferrat – when I discover my plump tender turbot is sprinkled with plankton.

Plankton. Yes, really. Plankton. Could there be a better moment for my first dive into the cuisine of filter-feeding whales? This is my third Michelin-starred feast in 36 hours and, despite the ravishing location, I fear I now resemble a leviathan of the deep rather than one of the Côte d’Azur’s beautiful people.

To compound the dietary felony I’m hardly burning off a single calorie. If I’m not at a dinner table, I’m in a car or a sumptuous hotel bed, having nibbled in-room treats such as sweet macaroons and gold-flecked chocolate sculptures.

I can’t complain. Extraordinary dining, worn leather car seats and Mariana Trench sleep are key ingredients on a unique road trip linking three of Four Seasons’ historic hotels. It may be called En Route to La Dolce Vita but the drive between Milan, Florence and Cap-Ferrat is unlikely to give you the 1960s physique of Marcello Mastroianni.

“A gloriously empty highway dotted with epic bridges carries us past San Remo and Monte Carlo…

Instead, it delivers period glamour. Ice bucket-loads of the stuff. The choice of classic rental cars jump-starts the coldest heart: a 1961 Giulietta Spider, 1956 Porsche 356 Speedster and 1958 Mercedes 190 SL Cabrio. If my immaculate 45-year-old Lancia Fulvia S Rallye looks like the runt of the litter, think again. The burgundy red sports saloon reeks of understated retro cool having won the 1972 World Rally Championship. ‘To drive it is to love it,’ coos Martino Pirman, CEO of specialist hire company Joey Rent. ‘It feels like an F1 car. It’s something incredible.’

As are some of his Four Seasons’ clients: one wouldn’t give his address as anything other than Bahrain. Pirman pushed for more but the man insisted, ‘It’s Bahrain. I’m the King. It’s mine.’ After resisting the urge to simply scrawl Clapham South, I pull away from the Milan hotel’s warren of elegant rooms and fading 15th-century frescoes. I putter past the tailors of Via Gesù, crunch the gears down Via della Spiga and confront Milan’s unforgiving traffic.

Happily, I’m not panicking alone. I’m with my brother-in-law Steven. Agreed, for peak 60s chic you need Anita Ekberg in a tight black number fresh from the Trevi Fountain, but she’d have lacked Steven’s driving chops – he owns a 1962 E-type Jaguar – and encyclopedic classic car knowledge. And she’d have soaked the upholstery.

Confession time. The price tag also buys a support car. Mine seems to contain two Vogue models but they are my mechanic Manuel in dark suit and Armani shades, and back-up driver, Cinzia (I know I sound like a 19th-century toff on the Grand Tour). They’ll sort out anything from directions and engine woes to driving fatigue. Jack Kerouac would have been appalled.

He’d also have been flattered. The Lancia is a complete attention hound. It draws admiring stares from fashionable Milanese belladonnas in Roberto Cavalli mini dresses and sunbathing carabinieri alike. We zip past Piacenza Cathedral before weaving along narrow lanes for lunch at Antica Corte Pallavicina, a 14th-century castle, once owned by composer Giuseppe Verdi.

As an aperitif to the Michelin-starred menu, there’s a cellar visit to study 5,000 culatello – dried hams in pigs’ bladders – dangling in hushed darkness: a prosciutto catacomb whose clientele includes Prince Charles. The proof of the pudding, or the ham, is in the eating, however. And the 37-month-old black culatello is truly buonissimo.

Taste buds sated, we push south towards Bologna, then rise into Tuscany’s Futa Pass: a dramatic leg of the legendary Mille Miglia Rally with vertiginous forests and hilltop cypress. Steven hits peak Clarkson, slaloming around corners, while I try to quell my nausea by pondering how Americans, accustomed to large automatic SUVs, cope with a tiny vintage Lancia without seatbelts – not compulsory until 1972.

We zip around Florence’s geometrical domes and marble six packs before checking into the Four Seasons: a living museum of frescoes and stuccoes wrapped around a 15th-century palazzo courtyard. After devouring chef Vito Mollica’s Michelin-starred take on regional dishes, I fall asleep beneath cherubs and angels, dreaming of vintage rally cars rising into the baroque heavens.

On day two, we awake to drizzle and a sadly broken-down Lancia. It feels just like home. Cue Plan B. Manuel tinkers beneath the bonnet and we take his Peugeot 208, with him hopefully catching up once it’s all fixed. Who’s complaining? You can’t feel short-changed as you turn north onto a coast sandwiched between cyan skies, mountains and the sparkling Mediterranean.

Climbing back into the Lancia in La Spezia we wiggle towards the gods on the Roman Via Aurelia, gazing down on the ludicrously beautiful villages of Liguria’s Cinque Terre. Lunch is yet another artisanal gem: wafer-thin focaccia filled with melted cheese. Restaurant Manuelina in Recco has used the same recipe since 1885, when they introduced it to ravenous Genoan aristos.

It’s high-fat fuel for the final stretch of the 1,200km route. The high-octane burn along a gloriously empty highway dotted with epic bridges carries us past Côte d’Azur honeypots such as San Remo, Menton and Monte Carlo, before taking the chequered flag on the Cap-Ferrat peninsula.

What a finishing line. Since opening in 1908, the Grand-Hôtel du Cap-Ferrat has hosted the A-list of the Riviera’s golden age including Picasso, Somerset Maugham and Charlie Chaplin. It’s a white and cream belle époque dream, bathed in diaphanous ocean light: a fitting full stop. Yet we can’t resist a final escape, taking the 1956 Porsche Speedster on a sunset spin past the peninsula’s yachts, umbrella pines and manicured villas: a last lingering lick of la dolce vita.

From £11,946, the completely customisable trip includes vintage car hire, support and three nights’ accommodation; fourseasons.com

Images: Vicki Grafton/Stocksy, Manuel Zublena, Ashley Ludaescher