I am unsure as to what exactly you mean, but I guess that you wish to know to what extent the emperor held authority (i.e how much did he have to say in the Empire as a whole).

It's hard to gauge precisely how much power the emperor possessed, but such things as the League of Augsburg and the Declaration of Pillnitz proved that the Emperor of Germany was no mere empty title, and that the Austrians could mobilise all Germany behind them if the need arose.

The fantastic British historian Peter Wilson has written a magisterial work, "War and German Society 1648-1806," in which he places the empire in context. Too often historians have stated that the emperor's effective authority came to an end in 1648 at Westphalia. But even as late as the 1770s the Emperor Joseph II was claiming, per his rights as emperor, to sequester the Electorate of Bavaria upon the extinction of the main Wittelsbach line.

Following the extinction of the Hohenstaufen in the second half of the 13th century, the Empire became increasingly decentralised, which at first glance makes a superficial contrast to the rising monarchies of the West. Yet, centralisation was occurring in individual polities, if not in the Empire as a whole.

Renaissance and post-Renaissance European diplomacy was predicated on a balance of power. The balance was necessarily imperfect. By far the greatest states in the system were France and Spain in the West, joined by the Ottoman Empire in the East. The divided German Principalities occupied the great central expanse between them. The fact emerges, however, that Italy was subjugated by Spanish and French forces repeatedly throughout the early modern period, and was a helpless victim in all the Great Power wars.

The Germans did not escape their share of invasion and depredation. But the Germans retained their political independence and succeeded in consistently expelling foreign armies from imperial soil throughout this era. This is quite different from the experience of the Italians, who were the reluctant hosts of Spanish and French armies even in peacetime, who incessantly siphoned away the wealth of the peninsula. We know that Germany possessed a ghostly unity in name, and we may also highlight the fact that Italy possessed no such unity. This is perhaps a coincidence, but I consider that most improbable.

In marked contrast to the Italians, the Germans developed nascent plans for collective defence. In 1495 the Emperor Maximilian I proclaimed the Ewiger Landfriede, the Eternal Peace. The purpose of this reform was to limit intra-imperial conflicts between the princes and secular aristocracy in the Empire and instead to submit their disputes to the arbitration of the Reichskammergericht, the Imperial Chamber Court. This was only a partial success, princes continued to war with each other. But if the Reichskammergericht decided in favour of one party, that party received powerful moral and legal support, usually resulting in sympathy and aid from the other princes.

Following fast on the heels of the Ewiger Landfriede, Emperor Max next enacted the reform of the Reichskreise, the Imperial Circles. In this reform Max divided Germany into “circles,” the defence of which was the responsibility of local secular and temporal lords. With the advent of the Reichskreise, Germany moved decisively, imperceptibly, towards military cohesion against external threats.

Some may see the Siege of Vienna as a turning point in the relationship of the Emperor with the German princes, but in reality it was merely a return to the partnership that existed between them in the days of Ferdinand I and Max II. Leopold fled the Hofburg and appealed to the German princes for support. They did not let him down. A combined German army under Charles of Lorraine and John George of Saxony was mustered within the walls of Linz to march to the relief of the imperial capital. The Türkenglocken, the Turkish Bells, calling all the Germans to rise up and defend their homes against the Turks, were pealing loudly across the Empire. The Germans responded to the summons. At the same time, the Polish King, John Sobieski, had answered the call and brought an army of his own.