I'm replacing battery on 2008 sedan (non X) and went to Costco and they gave me size 35 Interstate based on their lookup tool (got prior battery there 6 years ago.. surprised it lasted that long). Existing interstate battery is an inch longer and I couldn't see the label without removing it but specs were a little different. If you lookup 2007 sedan it has size 24F so obviously that's what I have. So the lookup tools at interstate and other sites are messed up for the 2008 model. Of course the 35 will fit but I'd prefer to stick with 24F since CCA is higher.