Rust

[Woodman411]

Luckily, In the UK, the warranty for Mitsubishi fitted accessories on a new car is 3 years/62500 miles.

I stand corrected. In the US, it's even longer: "All Genuine Mitsubishi accessories are covered by a limited 5 year 60,000 mile warranty when installed at the time of sale, or the remaining warranty up to 5/60 when installed after vehicle sale, or 12/12 whichever is greater."