According to Official Guinness Records,
The largest loop the loop in a car measures 19.08 m (62 ft 7.1 in) in diameter and was achieved by Terry Grant and Jaguar (both UK) at the Niederrad Racecourse, Frankfurt, Germany, on 14 September 2015. Terry was driving a Jaguar F-PACE, and the record was achieved as part of its début appearance in front of the motoring press. Read more: New Jaguar car and stunt pro Terry Grant defy gravity with largest loop the loop ever
For a complete list of 2015 records, please visit 2015 Guinness Records in Germany.