I had it in the back of my mind that Enterprise and Europcar were related undertakings, the impression dating back to when a friend was a senior executive with Enterprise in Florida - and I realise that we are talking about when INTA met in Orlando, which was probably about 1997. So it would not be surprising if things were now different in the car rental world. Indeed, back then Enterprise were not themselves in the European market.
In Enterprise Holdings Inc v Europcar Group UK Ltd & Anor  EWHC 2498 (Ch) (22 July 2014) the survey evidence related to the distinctiveness of the claimant's trade marks. In issue was the use of a stylised letter 'e'. Mr Justice Morgan considered the case-law (in particular, the Interflora cases) and judged that, despite criticisms raised of the survey in this case, it should be allowed. A useful review of the authorities, not a case that makes any new law.