Familiar with the 124 as our long-term steed, it seems wise to begin in the Mazda. Immediately and in every regard it feels a more modest, less showy sort of car. The outside is simpler in design - though it could be argued more appealing as a result - while the interior has none of the embellishments the Abarth forces you to take note of. Bizarrely it turns out to be the rev counters that give away most about the car's characters: the 124's is grey on red, featuring bold graphics and large numbers; the MX-5 is more modest and unassuming in design, a clear and crisp white on black tacho, but it's also the one with a higher redline...
There is fun to be had in the corners, though a standard MX-5 is far from an unqualified dynamic triumph. The steering gives very little impression of what the front wheels are doing but is also quite sharp off centre, which only seems to exacerbate the car's tendency to fall onto its outside wheel through bends. While great for imparting a sense of thrill and drama to the drive at low speed, it also means the car is very easily unsettled by mid-corner bumps because it's already loaded up with seemingly little effort. While fantastically balanced front to rear, a short wheelbase means you have to be quick if it is disrupted.
On less bumpy roads the MX-5 is better, both car and driver more settled; now you can enjoy its compact dimensions, the accuracy that comes with the limited-slip diff and - cliche alert - the wind in your hair on a sunny autumnal morning. It's all rather nice.
See that's perhaps the biggest revelation of the day, when it comes to formally assessing this pair. Despite everything, neither is really a sports car; treat them as such and you'll be disappointed by their shortfalls and lack of focus. But approach them as roadsters with a bit more pep than standard and they make a lot more sense.
Even with its racy graphics, swathes of Alcantara and ridiculous exhaust, this applies to the Abarth as well. It's certainly a more serious car than the Mazda, and being able to swap between them is an enlightening exercise, but that isn't to say it's perfect.
Unsurprisingly, the engine bolsters that attitude too. It's sometimes easy to forget that this little turbo packs just 1,368cc of swept capacity, so angry and belligerent is its demeanour. Well it is, right up until you experience the inevitable lag that comes with delivering 170hp from so few cubic centimetres. It's thrown into even starker contrast here, having come from the inertia free delivery of the Mazda.
The flip side, of course, is a mid-range that the MX-5 can't match, day-to-day performance that's easier to access and, to be honest, greater scope for being a bit of a scallywag. The additional torque - 184lb ft plays 148 - means the Abarth works its limits more readily than the Mazda. Given the cars are inherently so well balanced that's a pleasure: as a firmer car than the MX-5, the turn in doesn't catch the 124's rear out, meaning the line can be adjusted off the throttle by carrying some additional speed in, or slightly on the throttle by chasing the accelerator early in the bend and relying on that limited-slip diff. On dry roads it's a vice-free and entertaining introduction to front-engined, rear-drive dynamics, aided again by compact dimensions.
The problem? Firming the car's suspension up has highlighted the rigidity issues, the Abarth jiggling its way down a typical British B-road rather unpleasantly. It's a jolly good laugh in the right circumstances, engine gargling away and chassis adjustable to your want, but the flex isn't nice.
With this budget to spend on one of these cars, our choice and recommendation would be an MX-5 2.0 with money then spent at BBR to energise that engine further and address the suspension. But that's not the test, obviously. Of the two roadsters you see here, the Abarth is the more satisfying and enjoyable car to drive thanks to its torque and more focused suspension. Just. However the MX-5 wins this test - bear with - because, as tested, it's £7K cheaper. And the 124's advantage is too slight to justify that sort of premium, despite what anybody says. Perhaps the cheerier verdict is to say that both offer a unique take on the two-seat roadster despite their shared components, and there's evidently potential to easily make each better still. Let's see what else the aftermarket can conjure up...
ABARTH 124 SPIDER
Engine: 1,368cc, turbocharged inline-four
Transmission: six-speed manual, rear-wheel drive
Power (hp): 172@6,500rpm
Torque (lb ft): 184@2,500rpm
Top speed: 144mph
Weight: 1,060kg (unladen)
MPG: 44.1 (NEDC combined)
Price: £29,620 (As tested £32,210 comprising £600 for Portogallo 1974 Grey paint, £1,250 for Visibility Pack (LED headlights with automatic levelling and washers, Adaptive Front Light System, Dusk-sensing and rain sensitive wipers, rear parking sensors) and £795 for Bose Sound System)
MAZDA MX-5 SKYACTIV-G 2.0 SPORTNAV
Engine: 1,998cc, 4-cyl
Transmission: 6-speed manual, rear-wheel drive
Power (hp): 160@6,000rpm
Torque (lb ft): 148@4,600rpm
Top speed: 133mph
Weight: 1,075kg (with 75kg driver)
MPG: 40.9mpg (NEDC combined)
Price: £24,195 (As tested £25,145 comprising £550 for Mica metallic pearlescent paint and £400 for Safety Pack)