The Classic DTM class definitely needed a fabulous-looking new shape in its line-up, and the CA36a Opel Calibra V6 DTM gives us exactly that – a sleek coupe silhouette that couldn’t be more different to that of the angular Alfa Romeo 155 Ti V6 saloon. As you’d expect from Slot.it, the new addition is a faithful scale reproduction of the 1:1 – and the level of detail has been improved over even that of their debut Alfa.
The Opel Calibra V6 is a racing car built to race in the DTM (Deutsche Tourenwagen Meisterschaft) series in 1995. At that time the German Touring Car Championship was the peak of technology for touring car racing. The rules mandated cars with an engine displacement of 2.5 liters and 6 cylinders at most, derived from approved models and produced in no less than 25,000 units. The rules allowed deep changes to the car, provided that the external lines were maintained. This Slot.it model reproduces the works No. 9 racing at the Hockenheimring, driven by Manuel Reuter. [Slot.it]
Before even sliding off the cardboard sleeve, you’ll notice instantly that (aside from this being a gorgeous model!) it’s clear Maurizio and his team have been busy making small changes that offer big improvements. For example; the clear plastic vac-form that holds model in position while boxed has been redesigned to reveal much more of the car… a feature many might overlook, but one that those collector-types who’ll want to display their ‘unboxed’ model will no doubt appreciate.
In addition to the flamboyant arches, vents, ducts and spoilers that typify these mid-nineties DTM racers, fine details to the lightweight half-tray interior and driver continue to make this an impressive model to examine. There’s no denying – this is a great-looking car, and the closer you look at it, the closer you will look at it… this a model that somehow draws you in! A detail I particularly like is the roll cage, which features reinforced A-pillars and reaches right back to the rear suspension turrets.
If there’s one visual aspect of the Calibra which suggests that a compromise of sorts had to be made, that, as some have already pointed out elsewhere, is with regard to the wheels. Sure, with tampo’d tyre sidewalls and inserts, they’re accurate and look great – but the paint is a little tick, chips easily, and they just appear a little undersized compared to the arches. Now, if we can see this, then you can bet the Slot.it team were aware of it, too. So, it must have been a difficult decision for them to take; should they fit their larger 16.5mm wheels for a more realistic look, or maintain the proven, class-specific mechanical specification that they established with the Alfa?
It’s possible some will be a little disappointed with this decision, but I believe it was the right choice to stick with the ‘Classic DTM’ specification and a more performance-oriented product. This is a racer, after all – and part of a collection that shows every sign of growing into a large and exciting series. And, let’s be honest – are you really going to not buy one just because the wheels could be a bit bigger?
We’ve waited some time to have a running partner for the 155, so it seemed only appropriate to make this a back-to-back test – my concept being to take both models through a series of simple, reversible modifications and upgrades to examine the performance improvements while comparing one model to the other. Together with a club mate, we agreed to do 30 timed laps with each successive modification, wound back the clock some 20+ years, and got ready to recreate and relive some classic mid-nineties Opel vs. Alfa DTM moments!
Straight out of the box there’s basically nothing in it – despite my own Alfa being almost 12 months older than the Opel, the quality of the components mean that they offer exactly the same straight-line pace and similar cornering ability. Both cars ran smooth, blurrily-fast sub-10s laps – the only difference being that, when the magnet ultimately can’t hold on any longer, the Calibra tends to slide and tip upside-down, whereas the Alfa tumbles.
Magnets removed, we set about establishing a base time. It’s worth noting at this point that, although the Calibra body is a couple of millimetres wider than the Alfa, it arrived with exactly the same front and rear track width as the Alfa – so, the only real difference between them at this point is the much shorter stature of the Calibra.
Provided we drove without feeding the power in progressively, both cars remained relatively stable and, although neither model was hugely fast at this stage, it was clear that the Opel had a slight edge. An aggressive trigger-finger meant that the 150gr. magnet downforce from the motor was quickly lost which, in the Calibra, usually resulted in a slide before anything disastrous – given the same treatment, the 155 would pitch up onto two wheels and lift its guide out of the slot before tipping over. Another interesting handling difference started to emerge; the Opel was more likely to encounter ‘understeer’ on corner entry than the Alfa – the 155, although much easier to brake deep and turn quickly into a corner, could not match the exit speed of the lower Calibra and would frequently find itself leaving a corner not on four wheels, but on two and a door-mirror.
After 30 laps; Opel 11.676s, Alfa 11.931s (+0.255s).
Discussing the behaviour of both models, we agreed that the front ends felt a little light, and opted to make the first modification a simple braid-swap. Out came the stiff, springy originals and in went thinner, softer SP18. In the second session, we were delighted by how much of an improvement this made – lap times came down by almost half a second! Both cars became easier and more enjoyable to push confidently into and out of corners. Again, the Calibra favoured the faster curves while the 155 regained ground through the tighter sections.
After 60 laps; Opel 11.273s, Alfa 11.513s (+0.240s).
With tyre upgrades being common for club racing, running some laps after increasing mechanical grip also struck us as the ideal way to highlight the handling differences between these models – we opted for hand-out friendly Slot.it N18 tyres as these could be snapped on quickly and simply, requiring no gluing, truing, or any treatment.
What surprised us here was that the tyre change didn’t reduce the lap times as much as we’d expected. However, what it did do was make both cars more stable under braking and more controllable on their respective limits. Ultimately, increasing the grip highlights the Calibra’s strength and the 155’s weakness, marginally increasing the time difference between them.
After 90 laps; Opel 11.072s, Alfa 11.341s (+0.269s).
Determined to get the Opel under the 11s barrier, I decided to experiment with another simple modification – an SP23 tungsten ballast in the magnet pocket in front of the motor. Again, this didn’t make a drastic improvement to the lap times of either model, but it did help me achieve my Calibra goal while also making both cars a little more controllable and forgiving to drive.
After 120 laps; Opel 10.985s, Alfa 11.262s (+0.277s)
One final modification – left to last because it could only be made to the Calibra – was to take advantage of those extra millimetres and increase the rear track width. At the same time, we also added a few spacers to the front axles of each model to increase the front track width. Although this did allow us to squeeze a few extra hundreds of a second from the Alfa, it predictably offered more of an advantage to the Opel, widening the gap between it and its counterpart.
At this point, it was becoming clear that the setup changes were diluting the sensation of what made these cars unlike other Slot.it classes to drive. The Opel Calibra in particular was now beginning to feel strangely familiar; the dynamic was now much like how you might imagine a thinner Slot.it Gp.C with less downforce would feel. Given the similar mechanical specification of the two classes, I suppose this is to be unexpected.
Anyway, ultimately, after 150 laps; Opel 10.897s, Alfa 11.213s (+0.316s).
…wait, what – no 4WD?
With the 1:1 DTM racer boasting all wheel drive, some might think it’s a shame that Slot.it haven’t included their excellent clutched and belt-driven all-wheel-drive system as standard. Maybe, but the system can easily be retro-fitted – and extra parts (such as wheel trims) are bundled under the box to make the optional switch to 4WD that little bit easier.
..no longer a one horse race
While it seems clear that this new shape on the grid offers a performance advantage over its competitor, Slot.it have worked hard and done very well to engineer a built-in balance of performance that belies their differing outward appearances. As my testing has hopefully demonstrated, careful choice regarding what mods are made can increase enjoyment of these models – however, go too far and you risk undoing their good work, losing touch with what makes this class unique and so much fun.
With the addition of the fabulous Opel Calibra V6 DTM to their range, Slot.it have made the Classic DTM class a very hard series to ignore – I’ll certainly be doing my best to see to it that clubs in my area establish a racing series. Mind you, considering how easily my German slot friends will identify with these great-looking models, I doubt I’ll have to work all that hard. Given the steady progress this class is making, there’s every possibility that, in a year or two and after a couple more releases (hint, hint… Mercedes!) this will be a class to rival the popularity of many more established scale racing series.
Available in stores: May 24th, 2017
Once again, a big thank you to Maurizio and everyone at Slot.it for making this model available to me so quickly, and to HiP Duisburg for the track-testing facilities.