The electric car is a nice idea. It's cheap to run, environmentally friendly and increasingly fashionable. But then you look at the details. They cost a fortune, the battery doesn't work too well in the cold and, if you want to drive from London to Crewe, you're likely to run out of power in Birmingham.
England's batting line-up is a bit like that. The idea of a line-up including Jos Buttler, Joe Root, Ben Stokes and, indeed, Moeen Ali and Jonny Bairstow, sounds great. But in reality it has been leaving England well short of their destination time and time again.
Certainly it felt that way after the first day in Cape Town. An increasingly impressive half-century from Ollie Pope gave England some sort of foothold in the game. But an end of day score of 262 for 9 felt like a missed opportunity.
The fact that five of the top seven reached 29 but failed to pass 47 underlines that sense of waste. Those batsmen had, as Pope put it later "done the hard work" but failed to build on the foundations. "The hardest bit of batting is getting to 30," Pope said. "It's definitely a missed opportunity."
There will be those who criticise the desire or concentration of the team. And it's true that Ben Stokes, who looked as secure as anyone, seemed to suffer a lapse of concentration when he drove to extra cover.
In general, however, such explanations are probably a bit simplistic. Instead, this was a day which showed up the technical flaws of a side who have reached 400 just twice in the first innings since the end of 2017. That is a period of 26-and-a-half Tests. It is a record of consistent mediocrity.
Take the dismissal of Buttler. He had, as so often, looked pretty good. But when he received a decent ball that left him, he edged it, in part, because he was coming down the wicket with a view to manufacture a scoring opportunity. Would a man with confidence in his defensive technique have done that?
"There has been a tendency in the England set-up to trust natural instincts in the belief that talk of technique clutters the mind"
Much the same might be said about Joe Denly's dismissal. He had battled hard to reach 38 - at one stage he went 48 balls without a run - but was eventually undone by what appeared to be an arm ball from Keshav Maharaj which crept through the gap between bat and pad. That weakness, a propensity to leave a gate and allow himself to be dismissed by the ball coming in, is exactly what held him back during his first spell in international cricket a decade ago. It is frustrating that it doesn't appear to have been recognised or corrected.
And then there's the opening pair. Both Zak Crawley and Dom Sibley can reflect that they received fine deliveries; better, more experienced players may well have been dismissed by them. This is an excellent South Africa opening pair and England have not fielded a less-experienced pair of specialist openers (so excluding nightwatchmen) since the Oval Test of 1963.
But such is the lot of an opening batsman in Test cricket. That is why they must have techniques to withstand such bowling. And as Sibley and Crawley, both of whom move a long way across their stumps, played at deliveries they could have left, you were left wondering where the old-fashioned opening batsmen, the sort who could leave well and see the shine off the ball, had gone. Later Joe Root, prone to fall to the off side, was bounced out - not the first time he has been inconvenienced by the short ball in recent times - Sam Curran left a straight one and Dom Bess was punished for defending one that would have missed another set of stumps.
Even Pope had some fortune. He was dropped, a tough chance at short cover, on 21 and reprieved again, on 56, when it transpired that the bouncer he had hit to fine leg was actually a no-ball. But, as he ramped Kagiso Rabada for four over the keeper and marshalled the tail with more control than Buttler manages, he provided a reminder of how much potential he possesses.
Inevitably, after another disappointing display with the bat, there will be scrutiny of the county game. And it is true that the County Championship schedule renders it hard to prepare players for the rigours of Test cricket, though if it serves any purpose, it really should be to teach batsmen to play the moving ball.
Toby Radford, the former West Indies batting coach who this time last year was part of the set-up that secured victory over England, was in attendance at Newlands and he suggested the county game was not to blame. "Several countries have more consistent performances [in Tests] despite coming from weaker domestic systems," he said. Which is a fair point.
So perhaps we should look at the coaching set-up. It is hard to see a lot of improvement going on in the England environment. For all the talent of Moeen and Bairstow and Buttler, their averages of between 28 and 35 look pretty modest. All are between 29 and 32. This should be their golden age.
But again, that may be simplistic. We also need to question if players really buy into the need to improve technically. Whether there is a culture, in English cricket, of technical excellence. Or whether, over recent years, there has been a tendency to trust natural instincts in the belief that talk of technique clutters the mind. Of whether the "that's the way I play" mentality has started to excuse the absence of rigour exhibited by the likes of Steven Smith, Virat Kohli or Kane Williamson.
To be fair to England's batsmen, it takes time to implement technical changes. So while batsmen are involved in international series, they may be reluctant to tinker with something they feel at least gives them some chance of success. And with the gap between international series almost non-existent these days, the time for technical work and the hours of drilling that come with it are limited.
Let us also acknowledge this is a terrific South Africa attack. On this surface, offering a bit of bounce and a bit of movement off cracks that are likely to widen, they had enough encouragement to trouble the batsmen all day. We already knew Vernon Philander and Rabada were special, but with the pace of Anrich Nortje, who may be the find of the year, and the control of Dwaine Pretorius and Maharaj, they are a relentless force. They deserve a huge amount of credit.
So these dismissals were not as much due to lapses of concentration as they were a fine bowling attack preying upon weakness. Bowlers know that, against England, if they put the ball in challenging areas for long enough, the batting will collapse. It doesn't happen occasionally; it happens nearly every time. It's competence that breeds confidence; the other way around will only work for so long.
England are not exactly like the electric car. With technology advancing rapidly, there is reason to believe the electric car is the future. There is no such sign of progress from England's batsmen.