I think this is a most interesting infographic from the Royal Veterinary College. It says that the average lifespan of a ‘crossbreed’ (I assume they mean any non-pedigree moggy here) is 14 years while pedigrees live an average of 12.5 years. The difference is more stark with some breeds - Ragdolls have an average lifespan of 10.1 years while Bengals last on average a mere 7.3 years.
It’s possible, I think, that the situation for pedigrees is worse than these stats suggest. If we assume that most moggies are allowed outside while most pedigrees are indoor cats, then pedigrees are far less likely to die from traffic accidents. Despite their reduced risk of serious accidents, pedigrees still lead shorter lives.
https://www.rvc.ac.uk/media/default/vetcompass/infograms/150515%20how%20long%20do%20cats%20live%20-%20june2015.pdf