re = /(benz\s+[[:alpha:]]+)\d\w*/m
str = '2010 mercedes-benz sl500r
2010 mercedes-benz e550
2010 mercedes-benz glk350
2010 mercedes-benz c300w
2010 mercedes-benz 300
("2010 mercedes-benz sl",
"2020 mercedes-benz e",
"2017 mercedes-benz glk",
"2013 mercedes-benz c",
"2014 mercedes-benz 300")'
subst = '\\1'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html