Alfa Romeo Has Made A 'Sound Tunnel Index'

Having run both Alfa Romeo Stelvio and Giulia Quadrifoglio models over the last 12 months, we can confirm that 2.9-litre twin-turbo V6 sounds damn good in a tunnel. These are some of the last remaining sub-supercars that sound truly brilliant, and it seems Alfa Romeo is well aware.

The company has created what it calls a ‘Sound Tunnel Index’ ranking the UK’s “best driving tunnels,” putting in a surprising amount of effort in the process.

First off, Alfa asked fans to nominate their favourite tunnels, created a top 10. This was then sent to Sandy Brown, an acoustic consultancy known for its improvement works on the Royal Albert Hall. It sent experts to each of the tunnels to listen to a Stelvio Quadrifoglio doing its noisy thing from inside the car with the windows down, using the experience to give an objective measurement and a subjective ranking.

The two scores were combined, creating the ‘Index’. In the end, the 658-metre-long Penmaenbach tunnel in North Wales was deemed to be the UK’s best-sounding tunnel. This is thanks to the tunnel having twin one-way bores with a very good road surface and “a distinctive U-shaped profile.”

The 410-metre Saltash tunnel in Cornwall placed second despite being covered by a 30mph speed limit. “High road speeds are not essential to enjoy a tunnel,” Sandy Brown’s comments for the location note, adding, “Without the high levels of wind and tyre noise that can drown out the engine, the V6 Bi-Turbo was clearly audible with only a gentle throttle.”

In third was Beaminster in Dorset, rated highly as “the narrow U-shaped design of the tunnel means that drivers can hear the engine sound really clearly, despite the traffic.”

Before you fire up Google Maps and start planning a big road trip that takes in all 10, it’s worth pointing out that Alfa has a YouTube playlist featuring short sound clips of each. Just don’t expect full bore acceleration and multiple upshifts - a major manufacturer can’t exactly condone that sort of thing.