sentences:  Following Nissan's return to sportscar racing in 1995, motorsports division Nismo had been slowly climbing its way up the competition ladder to finally reach the top Le Mans prototype class.Starting with Skyline GT-R LMs in 1995, Nismo turned to developing the advanced R390 GT1 in 1997, which was effectively as close to a prototype as possible while still remaining street legal.With major rule changes in the GT in 1999, major manufacturers were no longer able to build homologation specials which resembled prototypes more than true GT cars.