There are a number of factors to consider when appreciating the situation. Besides knowing your opponent, other factors can be time , terrain and weather. The main consideration is whether you can convince (or trick) someone into engaging in the activity. Once that important element is met it matters not the type of vehicle; the task can be accomplished in any make or model. One should, however, be aware of the functioning and condition (of the vehicle and not just the participants). Safety should also be practiced. You should not be operating moving vehicles when engaging in sex and if you are engaging in sex, you should ensure that your vehicle has come to a complete stop and is properly parked.
As noted in a previous post, the weather conditions around Valentine's Day can less than ideal. While North American cities are now instituting idling bans, back in the day, it was common in Germany. Not only would an idling vehicle attract the attention of Polizei with a ticket, but it was not unheard of for local bürgers to take one to task, especially if your vehicle had Canada or USA plates. It quickly becomes habitual to turn off the vehicle when stopped. A light snowfall may be romantic, but it also can quickly cover the car windows providing a bit more privacy (as well as obscuring vision out).
One of the features of the Saab 900 used to be that the manual transmission was locked in reverse when the ignition was in the locked position. You couldn't remove the key unless it was in reverse. It was "supposedly impossible" to move the shifter out of reverse unless the key was on. I won't comment on the acrobatics that led to it, but the impossible happened. The situation was exacerbated because the vehicle had been unknowingly parked on a slight incline. With attention being paid to other activities, the windows (and view to points of reference) being covered with snow and a relatively smooth path of travel (good shocks and suspension on that Saab) it took a few seconds to become aware that immediate action had to be taken. The only damage was to the mood.
Lessons learned. Practice safe parking or get a room.