can anyone recommend a classic Fiat-friendly mechanic in West London?

The only ones I know of in London are Proiette in North London, who I have used before and have been around for years and are very good. Gonnella Brothers in South London who again have been looking after Fiats for years both are family firms.

There is one in Battersea called Firela but I haven't any experience of them.

Tony

Another person who works (and tunes) the 500s is: Mario Davoli--he runs a business called 'Mario Auto Repairs Ltd' . His business is situated under the railway arches opposite Golders Green station---917 Finchley Road, Golders Green, London, NW11---020-8731-6033/07956-442808.