According to Official Guinness Records,
The tightest parallel park in reverse has a space 34 cm (1 ft 1.3 in) larger than the car, and was achieved by Alastair Moffatt (UK) for Guinness World Records Day 2015 at Brooklands, Weybridge, UK, on 12 November 2015. Alastair used classic Minis for his attempt at Brooklands, which holds the Guinness World Records title for the first purpose-built motor racing circuit.
For a complete list of 2015 records, please visit 2015 Guinness Records in United Kingdom.