Descending a steep mountain road, we lean our vintage Vespa into a sweeping bend when a lush valley hundreds of metres below opens up before us.
This sight is so sudden and spectacular it's impossible not to utter an audible wow above the throaty gurgle of this immaculately-restored vehicle as the cool mountain air whips past our faces.
We have opted to ride together on the most breathtaking leg of our epic seven-day journey with Vietnam Vespa Adventures, exploring the rich and varying landscapes of southern and central Vietnam.
This stretch of road takes us from the old French colonial charms of Da Lat in the central highlands down to our final destination - the hustle and bustle of the beachside resort mecca that is Nha Trang.
Our riding ability and, in turn, our confidence has grown dramatically since the first day of the tour, test driving the Vespas on an unsealed, pot-holed but, most importantly, quiet road down by the Saigon River in Ho Chi Minh City.
Initially it's surprising how these stylish scooters heralding from the 1950s and 60s feel to ride. They are definitely not made of plastic.
It doesn't take long to get a handle on taking off in first gear, slowly letting go of the clutch, shifting back and forth into higher and lower gears, and braking.
If you can drive a manual car and ride a bicycle, you can do this. But the option is also there to drive a modern automatic moped.
"While we always offer people the option of an automatic, driving a manual Vespa makes for a truly authentic experience," says the tour operators founder Steve Mueller.
Steve, who was born and bred in the United States, bought his very first vintage Vespa - a pea-green and white 1968 model - in Vietnam for $US300 (NZ$422).
He has since built up a niche business restoring and exporting the scooters worldwide.
They were once status symbols for legions of French residents until their eviction in 1954, he says.
After the end of the war in 1975, and the country's subsequent closure to all foreign travel, the Vietnamese had to keep using and repairing them while, in other parts of the world, they were put on the scrap heap.
It's akin to the classic American cars still cruising the streets of Cuba.
Like a lot of fans of the BBC's Top Gear program, we love the episode where the guys travel the length of Vietnam on motorbikes.
But unlike Jeremy Clarkson and the lads, who had to use bikes that cost less than $US250 (NZ$351), we get to travel in style.
Atop our uber-retro rides, in single file we follow the lead of our tour guide Walter, a witty and knowledgeable Aussie who served in the army during the Vietnam War.
We immediately discover that concentration is essential, particularly when riding in city traffic or picking our way between cavernous potholes on back-country roads.
Yet it doesn't take long to feel comfortable on the scooter and feel the total freedom and exhilaration.
We are never thrown in the deep end - guides ride at the front and back of the group while mechanics are at the ready in a support van carrying the luggage, or even you, if there's a need for some time-out.
Unlike the chaotic scenes on Ho Chi Minh City's mish-mash of streets, teeming with mopeds sounding their horns, running red lights and driving on the wrong side of the road into oncoming traffic, most of our travel on this tour occurs amid rural areas.
Apart from one instance of children shepherding oxen along the road, traffic is thin and we even enjoy vast stretches of road all to ourselves.
From Vung Tau, we cruise along some of Vietnam's most scenic coastline where hibiscus bushes, bearing blood-red flowers backlit by sunrays, line the streets.
Mile after mile of gloriously empty blacktop unravels before us along a wild coastline where you can taste the salt spray from the ocean a few metres to the right, while high, barren dunes stretch inland.
When we reach the secluded fishing village of Mui Ne, we marvel at the riot of colour created by the highly-decorated boats on the azure-blue water as fishermen return with their catch.
After Mui Ne, we leave the coast and head for the mountains where the cool, calm of Da Lat awaits us some 1500 metres above sea-level.
IF YOU GO
Several airlines have flights between Australia and Ho Chi Minh City.
Vietnam Vespa Adventures offers one, three and seven-day tours departing from Ho Chi Minh City. Tour prices range from $US37 (NZ$52) per person on the one-day tour to $US2000 (NZ$2814) for a couple on the seven-day tour.
Meals and accommodation are included.
The writers were guests of Vietnam Vespa Adventures.