The biggest surprise about getting up close and personal with the extraordinary vehicles taking part in the 2012 SA Solar Challenge is that they are not as quiet as you'd think.
As the leading car, the world championship-winning Toray, built by the University of Tokai near Tokyo, pulled away from Sunday's first control point just outside Montagu after a compulsory 30-minute pit stop, it accelerated on to the road with a low, angry growl that was louder than the engine of the Toyota Fortuner that followed it.
That growl became a rising whine as the single-speed transmission rapidly picked up speed - uphill! - and disappeared over the crest, while the Tokai support crew (almost a dozen of them) rapidly packed up all their equipment, along with every piece of lint-free cloth, every shred of cellophane tape, and jumped into their van to set off after their baby, leaving the area noticeably cleaner than when they arrived.
The second surprise is that the top cars are not slow.
The Toray cruises at about 100km/h in strong sunlight and Tokai's arch-rivals, the private Kenjiro Shinozuka team, say their car is capable of 170km/h in short bursts - and that they intend to prove it with an attempt on the world speed record for solar-powered vehicles at the Gerotek testing grounds north of Pretoria at the end of the this year's SA Solar Challenge.
One would imagine that the Tokai guys would have something suitably scathing to say about that - the Kenjiro Shinozuka car is their 2010 SA Solar Challenge winner, which they sold to finance this year's Toray.
The third surprise is the cars' range: the top contenders can run a carefully-choreographed 800km, averaging about 65km/h, on battery power alone - and since the longest stage on this year's 5400 Solar Challenge is about 615km, the Toray could probably complete the course without any sunshine at all.
Indeed, there was no sunshine to be seen on Sunday morning as the cars set off from Cape Town's Canal Walk under threatening skies for Day 5 of the 2012 challenge, en route for their overnight stop at Oudtshoorn, their crews thankful for a rest day after battling to reach Cape Town in rain and strong winds on Friday.
But the Tokai crew were unfazed.
Just before the 8am start they plugged in a fresh battery pack (a wooden box about 600 x 400 x 120mm), taped fresh plastic sheeting over the all-too-vulnerable electronics under the solar panels and disappeared so quickly that they left the Fortuner support vehicle scrambling to catch up.
That support vehicle is one of the secrets of Tokai's success. It has a three-metre radio mast on the roof and two geeks with laptops in the back seat relaying weather and GPS terrain data to the Toray driver in real time, constantly running simulations of the remainder of the day's stage against wind, temperature and gradient conditions, and advising the driver on how to balance power usage against the output of the car's solar panels (which they also monitor in real time) so as to complete the stage as quickly as possible without running out of amps.
Another is the Toray's astonishing level of sophistication.
It's entirely made of carbon-fibre and expanded foam, with special, ultra-narrow tyres, and hand-made cockpit fittings and controls from the Subaru racing shop. Absolutely everything about the car is specially made; it's about two metres wide and more than four metres long, yet four skinny students can pick it up with ease.
Estimates of what it cost to build the car vary from $1.8 million to $10 million.
Equally astonishing is the team's attention to detail. At the stop the crew took the deck off the car so that they could change drivers without unsealing the emergency hatch, then used cellophane tape to lift each bug individually off the car's front end, and finally polished the entire car until it was as sparkling clean as when it was fresh off the trailer that morning, before taping every join in the body with cellophane tape to smooth the airflow over the car.
Which is why they are world champions.
The two Japanese entries are also way ahead of anybody else in terms of both preparation and energy efficiency; each has run flawlessly throughout the first half of the challenge, while few, if any, of the local entries - all from South African tertiary education institutions - have completed a stage without problems.
Even in strong sunlight their electric motors consume electricity faster than the solar panels can replace it. Eventually their batteries run flat and the cars simply stop, usually completing the stage on the trailer.
Many South African teams consider the 2012 Solar Challenge a learning experience, part of their preparation for the 2014 edition (the challenge is run every second year). But the mere fact that they are out there at all, competing against the world's best, speaks volumes for the spirit and dedication of these South African students.