Regars in Germany were of noble-class
Origon of Reger Germans as per the westerns Some historians believed that the roots of Regar Germans lie in the southern regions of Swabia, Bavaria, and Austria(form of these Words is same, as like Indian Raiger clans (Gotras): sawasia, Bavaria, Ausia, Kaushia, Jatia, Mauria, Maulia, Gaulia, Jaulia, Bhauriya, Jailia, Palia, Saulia, Dauria, Jainia, Nainia, Gumania, Tumania, etc.). It is also assumed that the German word Reger or Regar is derived from the Middle High German words “reigel” or “reiger”, where both the words are meant “heron( long legged wading bird = सारस)”. The Reger name was likely first bestowed on, someone thought to have the characteristics of a heron as a nickname, eventually becoming a hereditary surname.
Also as per German scholars, Regers found first in Bavaria, where this family became a prominent contributor to the development of the district(a revenue province) from ancient times. They were always prominent in social affairs and they became an integral part of that turbulent region as it emerged to form alliances with other families with in the Feudal System and the nation.
Etymology of the German word “Reger” questionable
Up to, whatsoever the etymology of the German word “Reger” has been established, is to be questionable. Because the word Regar is found in other European languages, having different meanings and is using as surnames in Europe and even in the U.S.A. also. But it can’t be hypothesized that the word Regar found in each European language has different etymology and Raigars, inhabitating in India are emigrated from Germany.
So many etymologies fail with respect to time, place and occupation
Unfortunately some pre-ancient words have been etymologized by post developed words. For example –
(1) Although “Raigar” is an ancient word of India and a derivation of the word “Raghu”. But it has been etymologized by a word Raanghar/Rang-gar(रांगड़/रंगगर ) , a newly developed word during the reign of Muslims in India. Whereas the word Rangad(रगड़ ) existed in the 7th century A.D. also.
(2) No “Gurjar” word was in existence, in the era of “Lord Krishana”. But in the Indian literature of medieval era, Lord Krishana has been adjoined with Gurjars, poeticlly. Although it may be assumed that some Gujar families may be sons of Nand Baba(nourisher of Lord Krishana). But Nand Baba and Vrishbhan(father of Radha, lovemate of Lord Krishana) can’t be assigned that they were Gujars.
(3) But it is correct that the origin of the English verb “brutalize(to make cruel)” is an inhuman and cruel act of Brutus, who killed his lord Caesar, deceitfully.
Thus each etymology may not be always true.
Supporting facts that the German word “Reger” is a aderivative of the Aryavarti word “Rag”
It seems that the etymology of the German word “Reger” may be related to the Aryan word “Rag”. Because Germans are also assumed descendants of Aryas and families of Rag Raghuvanshi Kshtriyas spread all over north Aryavart, middle Asia, western Asia, north Africa and Europe. For example- “Ragas” reaching in Yunan(Greece) were called “Ragai”. But the word Rag in Prsia remained as it is, even up to Alexander, the Great. Thus the etymology of the German word “Reger” should be reconsidered, in the context of the Indian ancient words “Rag” or “Ragar” or “Regar” , derived from the word “Raghu” as:-
Raghu → Ragh → Rag → Ragar → Rahgar → Rehgar → Raigar/Raiger/Regar/Reger
Where, Raghu was a femous Suryavanshi Kashtrias and he was Maharaja(Emperor) of Ayodhya in Aryavart (India) in the Tretayug as per Hindus.
Secondally, It is also a historical fact that Aryan Raghuvanshi Ragas ruled over somewhere in the joint land of Afghanistan and Pakistan . But after the fall of their kingdom, some Ragas migrated to Europe via Iran or Russia. Some of them inhabited in north-western India. Some of them settled in Iran. But reversely, some historians have assumed, that Rag city and Ragistan in Afghanistan had been developed by Ragas, who reached Afghanistan from an ancient Ragh village, which is traced out, near Tehran in Iran. But it is wrong aspect because Afghanistan have been an integral part of Aryavart(India) and Rag is an Aryavarti word.
Behaviour of Indian Ragas(Regar/Reger/Raiger), their assumptios and occupations
Although the ancestors Indian Raghuvanshi Regar Kshatriyas were big farmers and marshal servants in armies of local monarchies. But for the time being, Indian Regars have loosed their better social status and from last one and half centuary they have become devotees of Sant Raidasji, belonging to Chamar community. After independence of India they have also become the prominent devotee of the tomb of Baba Ramdeoji Maharaj, a Tomarvanshi Kashtrias. Besides it, a big part of Raigars are always having blind faith and belief in chanting and charming(भक्ति संगीत और जादू तन्त्र-मन्त्र ). They have been and are deep devotees of the Goddess of Power i.e. of Ma Kali and Ma Hinglaj. They have been also honoring chanters and sants without their caste discrimination for some past. Being sons of Kashtrias, Raigars have been worshipping Bhomyaji Maharaj(Beheaded Kashtrias warrior, who would fight, continuously without fallen on the ground). But it can’t be denied that still Raigars, genealogically, are clever, like heron. Some of Raigars may be heard, saying with sorrow that some Raigars can be characterized as persons, who always desire to get something, without any labouring, like a heron(सारस). Hence It seems that sons of Raghuvanshi Regar Kashtrias in ancient Germany were to be assumed to behave like a heron so that a synonym “Reger ” was to be bestowed to heron and it seems that the picture of heron seen in German Reger logo is a post creation.
Creation of some synonyms related to behaviour
(1) Although Pallav was a clan ruled over somewhere in Tamilnadu(Southern India) from 3rd to 9th centuary. But it is said that they would plunder or loot, enormously in their surroundings. Hence in the course of an interval the meaning of the word pallav as lutera(plunderer or looter) has been prevailed in that area due to behaviour of those Pallavas.
(2) Although Marwaries of Rajasthan(India) are well behaved. But in the money-matter they are tight handed. So in Bengali language it has been developed that Marwari means “rude” .
Thus it seems that due to clevering behaviour of Ragars immigrated in the German area, the word “reigel” or “reiger” has been develpoed as syonnym of the word heron.
That is, it is more reliable that the Indian ancient words, like “Rag”, “Ragar” and “Regar” in any form or with meaning reached Germany and other European countries. But later on, those words were pronounced and meant or associated, conveniently with something according to local dialects of various European countries and finally, they have been etymologized as Reger or Reiger or Regar or Raiger or Raigar.
Thus etymology of the word “Regar” found in various European languages, needs reconsideration.
Note: your valuable suggestions are inevitable.
 http://www.ancestry.com/name-origin?surname = regar
 Jati- Bhasker by Pt. Jwalaprasad Mishra in 19 th century A.D
 In Bal Ramayan by Rajshekher in 09 th century A.D. – It is mentioned that Rangads(रंगड़े ) became Ragai (रगये→रेगर ) afraiding by the Parsuram(someone in the 6th centuary A.D.)
Ragha: Raga(old Persian) or Ragai(Greek) is Rae, now a suburb of Tehran, which is very old habitation according to the local legends.
 Raghukul-Chintamani by Rajshekher in 09 th century A.D.
रघुवंस की जगत में, शाखा भई दस पांच ।
गुज्ज, रग, अभी, शक भिन्न भिन्न सतार्थ बांच ।।
गुज्ज(Gujj) = Gujar(Gurjar) रग(Rag) = Ragar(Raigar/Raiger/Regar/Reger)
अभी(Abhi) = Abhir(Ahir)
Raghuvans ki jagat men, shakha(Branches) bhai das panch(10+5=15).
Gujj, Rag, Abhi, Shak bhinn bhinn satarth banch(Understand, truely).
That is, Including Gurjar, Raigar, Abhir, Shak there were 15 main branches of Raghuvanshi Kashtrias in Aryavart(India).
 Annals and Antiquities of Rajputana(Con. Tad’s Rajasthan) by Con. James Tad in 19 th century A.D.
क्षत्रि साखा अनेक है, रघुवंश रग जान ।
कायथ खतरी बडगूजर तंवर जाट कर मान ।।
रग (Rag) = Ragar(Raigar/Raiger/Regar/Reger)
Kshatri sakha anek hai, Raghuvansh Rag jaan (Know).
Kayath Khatari Badgujar Tanwar jat kar maan(Understand).
That is, There were many branches of Kashtrias, like Kaysth, Khatri, Badgujar, Tanwar, Jat, Rag etc. But among them Ragas(Raigars) are Raghuvanshies.