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The sun is out, the sky is blue, there’s not a cloud to spoil the view – so what better way to make the most of the summer weather than to drop the top, fire up the engine and hit the road?
The Porsche 356C 1600 SC Cabriolet is the first of our threesome to arrive, greeting us with the rich sounds emerging from the depths of its four-cylinder boxer engine.
Just like their musical scores, the concepts of these three sun-worshippers are very different.
The Porsche, even in Cabriolet form, is a pure-bred sports car with only the familiar body shape carried over from the first 356/2 Cabriolet of the late 1940s.
Initially offered with a very manageable 40bhp from around 1100cc, the 356 as a coupé, Speedster and Cabriolet continued to develop in terms of driving dynamics over the ensuing decades.
From just 87mph flat-out at the start, by the time this 1964 356C 1600 Cabriolet was built it was topping out at 115mph – and the SC wasn’t even the sportiest model on offer.
In addition, there were effective disc brakes all around instead of the archaic drums of old.
Producing 95bhp at 5800rpm, the now 1582cc four-cylinder boxer motor that provided the sting in the tail revealed how much potential its basic design had from the cradle.
The open-topped version of the Borgward Isabella is a rare thing indeed.
While some 3575 examples of the 356C Cabriolet were produced in all available engine variants, a mere 200 Isabella Cabriolets in total were manufactured by the Cologne-based coachbuilder Karl Deutsch on behalf of Borgward, answering the prayers of fresh-air fanatics.
Later Isabella models are adorned with a diamond emblem in the radiator grille featuring ‘Borgward’ lettering, but in early convertibles, such as this, the name ‘Hansa 1500’ can still be seen – the brand under which the Isabella was initially produced in Bremen from 10 June 1954.
Legend has it that the feminine name was a spontaneous suggestion by founder Carl FW Borgward, after he was asked what should be written on the secret pre-production models when they were out being tested on the public roads.
Once it reached production, the enchanting Isabella was well received by fans of the marque and eventually became the most successful model in the company’s history.
Of course, the open Isabella that was born in 1955 is from a completely different bloodline to that of the Porsche.
Where the air-cooled Zuffenhausen creation is all purpose, muscle and flat-four engine roar, the topless Isabella is always elegant.
From the soft, rounded shapes of the coachwork to a cosseting interior ambience that is as comfortable as it is stylish, the Borgward makes for a charming travel companion.
In view of this, the fact that the engine is hardly a fireball is almost irrelevant. In bald figures, the in-line four-cylinder unit generates 60bhp from1493cc; combined with a relatively hefty kerbweight of 1040kg and a comparatively large frontal area that means a fairly conservative top speed of 84mph.
On paper, rather than being rivals, the Porsche and Borgward appear to complement each other perfectly.
You take the Porsche for an enthusiastic drive alone or with a single passenger, while the much more spacious Isabella, which is based on the saloon version, comes into play when a family outing calls.
No wonder these two cars have been in the hands of the same owner – for more than 40 years in the case of the Isabella.
In the 1950s and ’60s, seeing a Borgward Isabella or Porsche 356 Cabriolet was a special event, just as it is today, and to be able to own and enjoy one is lucky indeed – especially so for the super-rare open Isabella.
But there is a name missing from the file entitled ‘Open, rare, beautiful and built in post-war Germany’ – and it’s that of the three-pointed star of Stuttgart-Untertürkheim, the Mercedes-Benz 190SL.
Looking for all the world like a shrunken 300SL, the 190, like the Isabella, was born in 1955.
Mercedes-Benz gave its small SL a solidly built, luxurious interior and a body that was beautifully formed, featuring a number of flourishes carried over from its race-bred big brother such as the grille design, the ‘eyebrows’ over the wheelarches, the chrome bumpers and the basic proportions.
Under the sexy skin, however, the mechanicals were rather more prosaic with their origins not in the supercar 300SL but the stodgy W121 ‘Ponton’ saloon, which also donated its rear lights.
Accordingly, the 190SL was lumbered with the internal designation of ‘W121 BII’, where ‘BII’ meant ‘Series 2’.
With 25,881 examples built from May 1955 to February ’63, the SL is by far the most numerous of our trio.
The abbreviation SL stood for ‘Sport und Leicht’ (sports and light), while the number190 gave an indication of the cubic capacity of the in-line four-cylinder unit installed beneath its shapely bonnet, which on 1897cc and twin Solex carbs developed a useful 105bhp at 5700rpm.
Unfortunately, at 1160kg the 190SL is significantly heavier than the 1040kg Isabella or the flyweight Porsche, which brushes the scales at just 935kg.
Nonetheless, the Mercedes still managed a 109mph maximum – an impressive number at its launch in 1955, but a world away from those generated by the 215bhp 300SL, which was produced from 1954-’57 as the dramatic ‘Gullwing’ then from 1957-’63 caused a sensation asaRoadster.
But from the start this was never meant to be an out-and-out road-burner.
Mercedes-Benz itself referred to the 190SL as a ‘touring sports car’, which, given the key data on performance and unladen weight, seems a perfectly appropriate moniker.
Unlike the 300SL, with its tubular spaceframe chassis designed to take on – and win – some of the world’s great endurance races, the 190SL’s specification was rather more tame, with a steel monocoque and suspension derived from the Ponton saloon.
Nonetheless, although the racing genes were never intended to be part of the 190’s make-up, it was still able to show a clean pair of heels when necessary, as demonstrated by a competition version scoring a class victory at the 1956 Macau Grand Prix.
Most of the time, however, stylish travel with a touch of sophistication was the order of the day.
This approach was clear from the period advertising, which features a 190SL parked at the beach, with a handsome man at the wheel, glamorous partner gazing thoughtfully out to sea, while their lively fox terrier jumps around.
That’s how life was in the economic miracle. Cars were increasingly replacing motorcycles as a means of transport, and while the Teutonic masses were reaching for Volkswagen Beetles and the like, there was already a very wealthy class with the disposable income to afford luxury goods such as these convertibles.
Out on the road, however, the challenge of choosing between the three is made more difficult.
If the Isabella puts the focus on comfort and suitability for long-distance travel, the 356 SC marks the opposite end of the scale as a pure-bred athlete, while the 190SL sits somewhere in between.
Yet this rough classification is based not only on horsepower figures and outright performance, it is also underpinned by the chassis and suspension comfort.
Just as its curvaceous looks promise, so the Isabella impresses with its loping gait and quiet, relaxed driving experience.
After just a few hundred yards, you find yourself thinking about popping home to pack your swimming trunks, scooping up the family and heading off to Lake Garda, just as owners must have been moved to do more than 60 years ago.
And so modern is the driving experience, it feels as if it would manage it in one hop, leaving you unstressed upon arrival.
The technical description of the Isabella’s suspension doesn’t sound like that of a comfortable saloon car at all, but rather a sports car.
Like the Borgward RS sports-racer, the Isabella’s front wheels are suspended by double wishbones mated to coil springs, telescopic dampers and an anti-roll bar – an impressively complex set-up for the time.
There’s further modernity at the back, with a fully independent rear end employing swing-axles and radius arms.
No wonder, then, that the impressive ride comfort is accompanied by surprisingly good cornering behaviour.
The four drum brakes – the fronts with twin leading shoes – feel perfectly up to the (limited) performance.
When it comes to hurrying through curves of all kinds at the highest-possible speeds, however, the Porsche 356 SC sets the bar pretty high.
With powerful disc brakes all round it’s easy for the driver to pick the perfect braking point, then the compact sprinter from Zuffenhausen turns in eagerly and corners with real precision.
While the 75bhp 356C was equipped with Boge dampers as standard, stiffer Konis were employed for the sportier SC.
In conjunction with its 95bhp – the highest power output of all the overhead-valve 356 engines, with only the overhead-cam Carrera units offering more – the driver has fewer thoughts of a touring holiday, and more of a season ticket to the Nürburgring’s Nordschleife or a trip over the high passes of the Alpes-Maritimes.
Just as you expect, the Mercedes offers an appealing combination of its rivals’ qualities.
Smooth-running yet unexciting, and with elegant acoustic restraint, the 190SL gives the impression of an athlete in a pinstripe suit.
It is not as easy to give chase on a twisting road as it is in the Porsche, but extensive touring with a somewhat sportier gait than that of the Borgward is the default setting.
This is a car that feels as at home on the Promenade des Anglais in Nice as it does enjoying the spectacular mountain roads that surround the Côte d’Azur.
The 190SL employs high-quality materials in its construction, such as the aluminium of its bonnet and bootlid, as well as the outer skins of the doors.
Equipped with double wishbones and coil springs up front, in conjunction with low-pivot swing-axles to the rear, cornering feels safe with the limits high enough for the dreaded ‘tuck-under’ to feel far from reach at road speeds.
As a result, sinuous routes can be enjoyed with far more alacrity in the style icon from Stuttgart-Untertürkheim than in the Isabella, even if the bigger, heavier Mercedes feels rather more sedate than the Porsche.
The additional 10bhp and the extra torque from its larger-capacity ‘four’ simply cannot compensate for the tiny 356’s weight-loss programme – not least under braking, when the 190SL clearly loses metres to its lightweight Stuttgart neighbour.
That’s no surprise when you look beneath to find drum brakes all round, albeit finned for cooling like those of the 300SL to counteract the unpleasant sensation of fade as the temperatures rise.
Talking of rises, in recent years the values of all three of these Germanic sun gods have climbed to levels that underline their exclusivity.
If an Isabella Cabriolet appears on the market, you’ll have to plan on spending a solid £70,000 for a really nice example, while a well-maintained Porsche 356 SC Cabriolet has now passed the £200,000 mark and great 190SLs have long since broken through the six-figure barrier.
So disparate are their characters that a decision for or against any one of this group can only be made based on personal taste or affinity with one of the brands.
Soberly considered, all three are exclusive luxury items with a blend of glamorous style and sheer driving pleasure to enjoy on sunny days.
If the pursuit of performance is your aim, it has to be the Porsche: this is a car with fire in its belly, just waiting to be lit by a prod of the accelerator.
If style rather than substance is king, the dreamy Mercedes comes up trumps: not a thinly disguised racer like the Porsche, but a chic tourer that can still reward a keen driver on the right road.
But for its blend of looks, comfort and exclusivity, it would be the beautiful Isabella for me. It might only offer 60bhp, but it would still be my first choice for a family tour to the Italian lakes.
Words: Jürgen Gassebner
Images: Scoutsource Communication
- Sold/number built 1955-’63/25,881
- Construction steel monocoque, steel and aluminium panels
- Engine iron-block, alloy-head, sohc 1897cc ‘four’, twin Solex carburettors
- Max power 105bhp @ 5700rpm
- Max torque 107lb ft @ 2800rpm
- Transmission four-speed manual, RWD
- Suspension independent, at front by double wishbones, anti-roll bar rear low-pivot swing axles; coil springs, telescopic dampers f/r
- Steering recirculating ball
- Brakes Alfin drums, with servo
- Length 13ft 10½in (4229mm)
- Width 5ft 8½in (1740mm)
- Height 4ft 4in (1321mm)
- Wheelbase 7ft 10½in (2400mm)
- Weight 2557lb (1160kg)
- 0-60mph 13 secs
- Top speed 109mph
- Mpg 23.5
- Price new £2896
- Price now £70-140,000*
Porsche 356C 1600 SC
- Sold/number built 1963-’65/3175
- Construction pressed-steel platform chassis, steel body
- Engine all-alloy, ohv 1582cc flat-four, twin Solex carburettors
- Max power 95bhp @ 5800rpm
- Max torque 91lb ft @ 4200rpm
- Transmission four-speed manual, RWD
- Suspension independent, at front by double trailing arms, laminated transverse torsion bars, anti-roll bar rear swing axles, laminated torsion bars; telescopic dampers f/r
- Steering worm and roller
- Brakes discs
- Length 13ft 13/4in (4010mm)
- Width 5ft 5½in (1670mm)
- Height 4ft 3¼in (1300mm)
- Wheelbase 6ft 11in (2100mm)
- Weight 2061lb (935kg)
- 0-60mph 11.5 secs
- Top speed 115mph
- Mpg 33.2
- Price new £2277
- Price now £120-200,000*
Borgward Isabella Cabriolet
- Sold/number built 1955-’57/200
- Construction steel monocoque
- Engine iron-block, alloy-head, ohv 1493cc ‘four’, single downdraught carburettor
- Max power 60bhp @ 4700rpm
- Max torque 80lb ft @ 2400rpm
- Transmission four-speed manual, RWD
- Suspension independent, at front by double wishbones, anti-roll bar rear swing axles, radius arms; coil springs, telescopic dampers f/r
- Steering ZF worm and roller
- Brakes drums
- Length 14ft 4¾in (4390mm)
- Width 5ft 7in (1705mm)
- Height 4ft 10¼in (1480mm)
- Wheelbase 8ft 6½in (2600mm)
- Weight 2293lb (1040kg)
- 0-60mph 25 secs
- Top speed 84mph
- Mpg 31.4
- Price new £1426
- Price now £50-70,000*
*Prices correct at date of original publication