Good gravy! Hunting Scotland's best festive food in the epic M3

Cresting a hill, we spot the substantial factory of Simon Howie Butchers on the edge of Dunning, right next to Mr Howie's own postcard-perfect farmhouse. A local success story, he began with a small butcher's shop in the village and now owns a pair of branches in nearby towns. Oh, and supplies most major supermarkets and is the UK's biggest producer of haggis, turning out 1.3 million between Christmas and Burns Night alone.

The boss is away, but operations manager Robbie Crook shows us around. First, to the pudding room (best spoken like Adam West), where the aroma of black pudding sets our bellies rumbling. But it's haggis we're here for - minced pork, beef and lamb offal, oatmeal, barley and a blend of seasonings combined to make Scotland's hearty national dish.

They also make gluten-free and vegetarian versions; Crook says the latter is often a "gateway haggis" for those new to the delicacy. Haggis balls are dipped in batter and rolled in breadcrumbs to make bite-sized bon-bons, popular as a Christmas starter and therefore a strong foundation to our menu.

Then, in the sweet- and smoke-scented bacon room, Crook explains how streaky cuts of pork belly are hand-rubbed with a dry cure, aged for up to 10 days, smoked for four to six hours over wood chips, machine sliced and then wrapped around pork chipolatas to create our first mouthwatering side dish: pigs in blankets.

Two items secured and it's back into the M3 as the wind picks up and the rain starts to hammer down. A hedgerow-tracing B-road leads us across a swollen River Earn, busy with salmon heading west to spawn. Canopied stretches begin to litter with falling branches, and water collects by the verges – Morgan Super 3 weather this is not.

The BMW's rear-biased but fully variable, multi-plate clutch-based M xDrive system is coping brilliantly, faithfully laying down all the power it is asked for and confidently tracing arcs without a twitch of the steering.

The exception is standing water, though, upon which the CS gets skittish. We're on the least track-focused of the three tyre options available, but they're working beyond their comfort zone here.

We skip past Crieff before rising into the wilds of the Sma' Glen, lined with crimson ferns and heather, then up again into a fast section of exposed uplands towards Amulree. Set in its supplest mode, the M3's adaptive suspension keeps us comfortable save for noticeable reactiveness over a couple of bobbly sections on the descent into Dunkeld.

Although sodden, Dunkeld is a gem. Thomas Telford's seven-arch bridge spans the handsome River Tay and leads us into the tiny, ancient town. On a narrow lane to the 700-year-old cathedral, we shoehorn the BMW in front of The Clootie Dumpling cafe in search of our sweet course.

Mike and Jacinta Cairney's cafe specialises in the eponymous Scottish spiced cake made to the recipe of Mike's mother, latterly known as Granny Margaret. "Mum would make clootie dumpling for our birthday tea, with a 10 pence piece inside.

If there was any left, she'd fry it up the next morning with bacon and eggs, haggis, black pudding and Lorne sausage," recalls Mike. This was a fairly typical childhood experience, and many of the cafe's customers come for that nostalgia. Clootie dumplings are also served at weddings, Christmas and Hogmanay.

Jacinta describes her process. A dry mix of flour, fat, breadcrumbs, raisins, sultanas, brown and white sugar, ginger and spices is beaten by hand with treacle, eggs and milk. A cloth - or 'cloot' is boiled in water to scalding point, then laid out and sprinkled with flour, which forms the chewy skin.

The dumpling mix is poured in, the cloot tied tight and the whole shebang boiled for four hours. I'm presented with a generous, warm slice, with cream. It's a revelation - mellower and much lighter than Christmas pudding - and we're delighted to come away with an enormous half clootie dumpling.

In full storm conditions, we drive east towards Angus on saturated country roads. There's so much standing water we may as well be peering from the cockpit of an ekranoplan. By necessity, the next 36 miles pass slowly through 200-metre visibility, the 3.0-litre straight six's pair of mono-scroll, 2.1-bar turbos reduced to a breathy sigh.

We're glad of a warm welcome at South Powrie Farm, just north of Dundee, where we've come to talk turkey with Thomas and Susannah Pate. Theirs is one of a handful of farms across the UK appointed to rear the KellyBronze breed that is prized for its superior flavour. 

The Pates keep 600 turkeys, which arrive as day-old birds that could all fit in the back of the M3. We'll only be needing the one, though, which is just as well because they grow as heavy as 15kg. We'd planned to meet the flock, but they're wisely hiding from the torrent in their field shelter, so we plan to return the following morning when the clouds are more continent.

We're greeted at 8am with a chaotic reveille of clucks, squawks and yelps as the highly inquisitive turkeys perform a waddling sprint to meet us in their two-acre field of woods and long grass. Their feathers truly are bronze-like, with a deep brown, almost rainbow-sheened plumage.

The adolescent stags have snoods and wattles - puce globs of skin above and below the beak - and proudly display their tail feathers. But gender is no predictor of social status, which is decided by a literal pecking order: the dominant personalities nip feathers from their inferiors. One ambitious character has a nibble at my wellies, then my leg. I resolve to meet it again in late December... In the meantime, we take a whole frozen turkey with us.

Immediately before Christmas, the Pates sell fresh turkeys direct to the public from the farm and collection points along the east coast - one of which also grows and sells veg, so we head there next. We cross the Tay Road Bridge into Fife and, at last, are presented with a chance to properly stretch the M3's legs.

In its engine's hottest mode, the CS is largely bridled below 3000rpm, but beyond that there follows acceleration so forceful and relentless that it feels almost exponential. With the exhaust flaps open, rising revs bring ever-louder bass and mounting inductive aggression: certainly dramatic, although not spine-tingling. The sweeping A92 is meat and drink, consumed with pace and balance as the M3 melds itself to the surface.

It is less at ease on the more technical minor roads thereafter, both in terms of cornering inertia and suppleness, but it's still riotous, with inflatable bolsters on the bucket seats holding us firmly in situ.

With the CS nicely warmed, we perch it outside Pittormie Fruit Farm, a compact, 35-acre site run by Euan Cameron and family. The shop is shuttered after a busy summer of fruit sales, but the egg shed's honesty box is kept jangling by a steady supply of winter vegetables, also sold to restaurants and greengrocers.

Cameron has an appealingly laissez-faire attitude towards growing his varied crops, with minimal fertilisers and neither fungicides nor irrigation. He is uncomplimentary about the conformity and lack of seasonality of today's supermarket produce. "I don't force things," he says. "I like it to get there naturally. I don't care if something is fugly."

His ATV shoogles us to the multicoloured brassica beds where he unearths for us a well-stocked, Bosworth-variety sprout tree, studded with firm, green nuggets of Christmas joy. Cameron then whips an unfamiliar, purple-green mass of leaves from the soil-it's kalette, a sprout-kale hybrid whose florets cook to a crisp as a nutty alternative for sprout-haters.

We're in the right place for tatties, too. Using an old harvester Cameron re-engineered himself, a modest plot of just two acres yields 22 varieties, many of which are niche. His top picks for roasting are drier kinds including Kerrs Pink and Golden Wonder, but the waxier Wilja is his favourite (boiled, oiled and air-fried), so, along with a few carrots, we load a generous bag through the BMW's rear window hatch.

With tomatoes and apples to munch en route, we continue south across Fife's typical rolling farmland on gorse-lined B-roads. The perpetually faithful steering is always best in its heavier, intuitive Sport mode - Comfort's lightness mismatches the car's size and weight.

We're carrying some speed, and the middle of the three gearbox settings in both Auto and Manual modes suits best. In the former, it allows enough revs without needlessly hanging in the upper reaches, while in the latter it's responsive enough without the full-body convulsions you get with upshifts in the most aggressive mode. The optional, £8800 carbon-ceramic stoppers are both easily meted and thoroughly ruthless.

The main coast road halts our path and we pull up at a converted stone stable block that's home to Futtle Brewery, named for an onomatopoeic Scots word for pebbles thrashing in the surf. Much of the big, open room houses stainless steel fermenters brewing high-quality, unfiltered organic lagers, wheat beers, spelt beers and pale ales.

In the corner, Ethan Russell Hogg is tending bar and keeping the LPs spinning. "Our beers are fresh and different and take a long time to brew-six to eight weeks, sometimes more - which makes a higher-quality beer," he says.

Unusually, they use raw, whole-leaf hops rather than pellets or oil, plus a mix of malted and unmalted grains and locally foraged plants and seaweed for flavour. Intriguingly, there is also a 'coolship' - an open-topped copper vessel for brewing Belgian lambic-style 'wild beers' that ferment after absorbing whatever yeasts happen to be in the air before ageing in old cider casks.

The first two batches will be bottled by Christmas. For now, we pick up some cloudy but light Table Beer, Futtle's original ale, to accompany our feast.

Our journey ends with a solitary mile to the idyllic fishing harbour of St Monans and a pastel blue, two-storey building set into the harbour wall. Lashed by waves on one side, East Pier Smokehouse is an acclaimed yet accessible seafood restaurant.

In the dining room and panoramic roof deck, they serve mackerel, langoustines and lobster all landed just yards away, plus Cullen skink, crab, sea bass, octopus and more, with takeaway available, too, providing the kitchen can manage it. Chef and co-owner James Robb is being modest when he refers to the restaurant as "a small, simple affair" - but that's certainly how I'd describe its most unique feature: a traditional smoker, no larger than a cupboard, that opens to the street.

In use since the 1940s, its walls are now encrusted with tar. There's a pair of angled channels at the bottom where Robb burns oak and beech sawdust for 36 to 48 hours - depending on the weather - to cold-smoke West Coast salmon.

Compared with modern smoking machines, it's an extremely fickle, old-school approach that sometimes requires midnight check-ups, but Robb has mastered the process to produce both traditional and burgundy-hued, beetroot-cured salmon for serving in the restaurant and selling direct to the public.

I'm treated to a plate with bread, butter, lemon and capers: it's sweet, smoky, firm and the best I have ever tasted. It's a fine way to complete our 10-piece Christmas dinner: made in Scotland, express delivered by Munich.