It's a rubbing of
此君車. The proper translation is
This (is) the master's chariot
as said in Wang Dingwei's answer. The man on the chariot could not be a king, because the structure of the chariot was just too poor for a king.
Update Jun 20, 2018: add the very original source of the rubbing.
I am not an expert on stone carvings (畫像石) of Han Dynasty, but I happen to have read some volumes of the series book Chinese Stone Carving Corpora – Stone Carvings of Han Dynasty in Shandong (中國畫像石全集: 山東漢畫像石). I will try to cover information of this rubbing as complete as possible, but be aware, my conjectures are not necessarily correct.
Where did the rubbing come from?
In the 1970s, 中国国际书店 (China International Book Store, now the name is changed to 中国国际图书贸易总公司, China International Book Trading Corporation) compiled a catalog for a collection of rubbings (the rubbings were made by 汲古閣 in 1960s–1970s):
中国拓片 Chinese Rubbings
The preface of this book said:
The rubbings exported by China International Book Store mainly include two categories: ink rubbings (black and white) and color rubbings. They are well made and the image and rubbing ink can keep the original. They can serve art lovers for collecting and appreciating purpose.
We have the rubbings listed in this catalog in stock. Orders are welcomed.
The rubbing in the question is one of them listed in this book, numbered "BS-2014" with a brief description:
Rubbed according to the stone carvings of Han Dynasty in Jiaxiang, Shandong Province. One chariot. The rider is the master, taking the rein pulling the horse; the follower is the servant, holding the canopy aloft.
Other similar rubbings of chariots in this book are
功曹車 Head Clerk's chariot
尉卿車 Head of Security's chariot
Story behind the rubbing
Before introducing what this kind of rubbings were used for, let's enjoy the "此君車馬" rubbing first:
Stone carving on the West Wall, Front Stone Room, Wu Family Shrine
In the first year of Jianning of Emperor Ling of Han (186 AD)
Height: 117cm, Width: 203cm
Unearthed in the north of Wu Family Village, Jiaxiang County, Shandong Province, in the 51st year of Qianlong of Qing Dynasty (1786 AD)
Kept in Preservation Institute of Wu Family Shrine of Jiaxiang County
The original number of the stone is 前石室五 (5th of Front Stone Room). There are three stories in the picture. Double diamond patterns, Connected arc patterns, flower patterns and horizontal bars separate different stories. On the top story, the acme, Queen Mother of the West sitting on two crossed dragons is carved in the middle, with bird men, Jade Rabbit, Toad, supernatural birds and beasts at both sides. On the middle story, twenty-two apprentices of Confucius with costumes standing respectfully facing leftwards are carved. One the bottom story, a row of chariots heading left are carved – The image is damaged, and there are titles "調間二人" (two Tiaojian's), "此騎吏" (This cavalry [is a] officer), "此君車馬" (This [is] the master's chariot and horses), "主簿車" (Head Clerk's chariot), "主記車" (Head Secretary's chariot), and there's one man cordially seeing them off on the right.
(The "此君車馬" part. Full image can be downloaded here (Format: djvu).)
As said in 中國畫像石全集 Chinese Stone Carving Corpora (vol. 1), "中國畫像石概論 An Introduction to Chinese Stone Carvings":
The stone picture carvings of Han Dynasty existed in stone shrines, stone watchtowers, tombs, and stone coffins, depicting the religions at that time as well as the master's social status and life situation. After the era of the three kingdoms and Jin Dynasty, this kind of artistic technique, stone picture carving, declined and was gradually replaced by murals. From Northern Dynasty to Sui, Tang, and Five Dynasties, only on coffins and coffin beds could stone picture carvings be seen. And afterwards, only some stone boards had similar artworks, but they were mainly single frame expressed by the line carving technique, and included plans of some astronomic graphs, maps, cities, palaces, government offices, temples, and parks. However, for the art form of stone picture carving, it almost came to an end.
To be continued ... and now two years have passed. It doesn't actually cost me two years to find the answer to my doubts, but driven by the hard life (not really) as a software engineer, I've nearly forgotten the responsibility to finish this answer. Fortunately, the fate leads me here again.
Conclusion: the rubbing is a modern copy to a relatively old copy to the stone carving in 武梁祠後壁 (back wall of Wu family cemetery, Jiaxiang, Shandong Province, China), which dates back to the mid-2nd century. Currently, the stone is kept in 嘉祥縣文物保管所 (Jiaxiang cultural artifact museum).
The relatively new rubbing (real rubbing but not copy) is
OP's "rubbing" is at the bottom left corner. Zoom in:
此君車 does not appear on the original source, so it is a mistake that might come from some other copies.
As you can imagine, there must be many versions of rubbings and copies appearing in history because the stone is so old. In fact, OP's "rubbing" probably copied the image from a relatively old book 金石索 (Research on Epigraphy) authored by Feng Yunpeng and Feng Yunyuan in 1836. This book contained copies of epigraphs. Note that again, there's no
此君車 on this old copy either.