The reason why Vanwall won the constructor´s championship was rather because usually one of their cars did make it through to the end and then usually beat the Ferraris when only the first car of each make did count towards the championship.
On the other hand it becomes also clear to me that Hawthorn won the championship because he made a lot less "driver errors" than his team mates and thus could make real use of the good reliability of his car.
To me, the above is the essence of the 1958 Championship season.
Hawthorn in some races was able to nurse his car to the finish with a slipping clutch(Italy), no brakes(Portugal), low oil pressure(Argentina & Britain), and at Spa his engine broke as he crossed the line for second place(behind Brooks, whose gearbox tightened up at the last corner, and ahead of Lewis-Evans whose right front suspension broke on the line).
Moss, however, had three engine failures which resulted from over-revving, according to 'Jenks' in a tribute to Vanwall in "Motor Sport" of December 1958 - also repeated in his book "A Story of Formula 1".
Monaco - valve cap jumped out due to over-revving
Spa - missed a gear-change - bent valves
Silverstone - wrecked engine - valves touched the pistons once too often!
If Moss had finished in the top 4 in any one of these races, his points score for 6 races would have topped Hawthorn's.
Jenks' comments on the Vanwalls at Reims was that the cylinder heads were warping because the engines were running at full throttle for longer than they ever had done before. Moss finished second, but Brooks broke his gearbox, and then took over Lewis-Evans' car only for it to suffer a broken valve. Vanwall entered only 2 drivers for the German GP because they didn't have an engine for Lewis-Evans after a run of test-bed engine disasters.
A couple of other comments should be made - Moss won the Argentine GP in Rob Walker's 2-litre Cooper after Ferrari were expecting him to have to make a stop for tyres, and couldn't get Musso to speed up after they realised Moss wasn't stopping!
I recall from the time that there was some complaint from the British teams that they had insufficient notice of the confirmation of the 1958 Argentine GP date. Not surprisingly this seemed to vanish after Moss won the race. In fact, in the previous 5 Argentine GP's, the fields had included all the teams competing at the particular time, i.e Ferrari, Maserati, Gordini, Lancia, Mercedes and even Cooper with 3 Cooper-Bristols in 1953. But not Vanwall or BRM. So the GP went ahead with 3 Ferraris, 6 private-owner Maserati 250Fs and Walker's Cooper. Any other Argentine GPs since then have had a full field of runners, and I'm not sure any of the British teams(Cooper included) were considering entries in 1958 anyway.