I dont know too much about the Le Mans race but the sponsorship of West Ham FC is bringing the XL.com brand to a wider public.
The last airline I worked for had a flight to a destination also served by Easy Jet, the tickets were £ 5 cheaper and the flight departed at about the same time usualy half full when Easy Jet would be overbooked. Why ? it was because of the companys lack of publicity.
Getting the company name on a race car or a football shirt is very cost effective publicity that reaches a large section of the public, it only takes a small number of the people who see the XL logo to book flights to make this form of publicity very cost effective.
So lets look past the standard British envy trait and find out if this support of sports teams is putting bums on airline seats, if it is then it is money well spent.