Price £23,995
MPG 44.8
Top speed 129mph

We know a car is a substitute for all manner of personality defects. They're the six-cylinder seawall we erect to shore up our mounting insecurities. And nothing does that better than a big-engined convertible. The mighty rumble from its exhausts tells the world we are solvent, virile and, yes, awesome. We park next to miserable mid-size saloons in company carparks and watch the oppo limp away… pulverised. Booyakasha! So how come I always feel like a knob when I drop the top?

The reason, I think, is that people who purchase convertibles are overly concerned with their image. They buy ludicrous red sports cars made by Italians; they wear sunglasses in the shade; they put too much gel on their thinning hair. But one thing they don't do is buy Vauxhalls. So this Cascada, a new convertible from the Luton-based company (which last year celebrated its 110th anniversary), comes prejudice-free. No one will think you're a right tool in the grip of an existential crisis. Leaving you free to savour the enduring joy of driving an unpretentious car with the roof down. I am convinced this pleasure goes right back to the days when our hairy-faced ancestors roared about in open chariots. Even then, though, there must have been jumped-up poseurs with chrome wagon wheels, flashing a thigh in a short leather tunic. Maybe in white, with tassels…

So, for those of you looking for an unassuming convertible, you'll find the Cascada is more than up to the job. It's a well-made and thoughtfully designed car. With the roof folded neatly away, it has all the clean functionality of an elegant yacht's tender. The roof is fabric – those folding hard-tops are so last year – and this softens and feminises the car. You can also have it in a stylishly contrasting colour. My test vehicle had a chocolate hood on a pale sapphire body – gorgeous.

Inside, the dash is wrapped in stitched leather, the seats are deep and the controls are nibbed in quality rubbers. The only oversight is the crappy red dot-matrix display between the dials, which looks like it was nicked from a 70s microwave.

You could be forgiven for guessing the Cascada is nothing more than a roofless Insignia, but it has been designed from the chassis up and doesn't share a single panel with any other Vauxhall. The car comes in two trim levels, SE and Elite, and there's a range of engines to choose from. The two bestsellers will be the 1.4-litre petrol, which is slowish yet refined and pleasant, and the gutsier 168bhp 2-litre diesel. Vauxhall claims 44.8mpg for the former, which would be miraculous for a petrol engine, while the latter will do a more plausible 50-plus miles to the gallon.

As with almost all convertibles the boot is fairly cramped, but the car does have four decent full-size seats – you don't have to be a yoga guru to tuck yourself into the back. But visibility out the rear is shockingly poor. At one point I had to open the roof in order to reverse properly.

This isn't a car you'll want to drive hard. It's a smooth, understated cruiser which lets you get on with the work of soaking up the rays without the glare of bad publicity.

Email Martin at martin.love@observer.co.uk or follow him on Twitter @MartinLove166