First McLaren to feature a V6 engine and the first electrified model of the Woking brand to be mass-produced (not counting the limited P1 and Speedtail), the McLaren Artura marks the beginning of a new era at McLaren.
In turn, the Ferrari SF90 Stradale it is not far behind when it comes to “internal landmarks” and inside Maranello's house it is “only” the most powerful road model ever, being also the first to be produced in series, without limitations, unlike the LaFerrari.
In common, both are plug-in hybrids and share a “little curiosity”: neither of them sees their respective gearboxes (double-clutch and eight-speed in both cases) incorporating the traditional reverse gear.
a matter of weight
But why do without the reverse gear ratio? In a very reductive way, doing away with reverse gear in this type of hybrid makes it possible to avoid redundancies and even a small saving in weight.
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As you know, plug-in hybrids are much heavier than models with only combustion engines — either by adding one or more electric motors and, above all, by the presence of batteries that power them — so take every measure to keep this weight contained. are welcome.
Furthermore, if, in a “normal” car, excess weight is already problematic — more inertia and compromises the dynamics —, in two supersports as focused on performance as the McLaren Artura and the Ferrari SF90 Stradale, the extra weight is an issue crucial.
In the case of the British model, despite the presence of the 7.4 kWh battery and the electric motor, its weight in running order is below 1500 kg — it weighs 1498 kg (DIN). The SF90 Stradale, on the other hand, sees its hybrid system add 270 kg and the total mass rise to 1570 kg (dry, that is, add at least 100 kg for all the fluids necessary for its operation).
A small contribution to alleviating the impact of the electric machine's weight was, precisely, the relinquishing of reverse gear. In the case of McLaren, it was the way found to offer another relationship to the transmission without increasing its weight. In the Ferrari, however, it saved a total of 3 kg compared to the conventional double-clutch transmission they already had.
How do they back off?
By now you must have asked yourself: “ok, they don't have reverse gear, but they can back off. How do they do it?”. Well then, they do it precisely because they are plug-in hybrids, that is, they do it because they have an electric motor powerful enough for this task.
As in electric cars (which, as a rule, do not have a gearbox, only a one-speed gearbox), the electric motor can reverse its polarity, moving in the opposite direction, thus allowing Artura and the SF90 Stradale to back off.
In the case of the Artura, the 95 hp electric motor housed between the gearbox and the crankshaft, in addition to ensuring the functions of "reverse gear", supporting the combustion engine and driving the car in 100% electric mode, it also has the ability to smooth cash ratio changes.