You're right, I thought the closed cart was the 2.
According to the B&Q spec, it has the limited warranty: 10 year Warranty - Porcelain enamelled lid, cast aluminium components & burners-10 years. Cart, spark ignition, cooking grate, flavouriser bars & all other parts-2 years. I also checked the Weber website and its the Spirit II that is fully covered, not the Spirit range.
Do check the 10yr warranty though, as it is limited. I am not being negative, as I too wish to purchase a Weber at some stage, I just wanted to point this out.