I haven't brought mine in for servicing yet, but my dealer (Santa Monica) told me that they provide loaners (either LRs or Jags). Hopefully, that wasn't just a bunch of smoke : )
OK - just had my car in for its first repairs (Santa Monica LR). The dealer gave me a Jaguar XF with 12,000 miles on it. There might have been other choices, but they offered the XF and I was happy to have it. The service department cashier is also an on-site Enterprise desk, and they process the loaners using Enterprise paper work. The told me to bring it back with approximately the same amount of gas, but told me they only charge $3.80/gallon for premium if you bring it back with less (which is about 30-40 cents cheaper than buying premium at an LA gas station).
BTW, the XF is an incredibly fun car to drive. I was tailing a Ferrari through Topanga Canyon yesterday and then took some even windier, more deserted roads to have a little fun. It's got the same engine as the LR4 but weighs about 1/3 less. It's got the 6-speed paddle shifter transmission (with the pop-up dial control), which shifts really quickly, and the suspension is really well sorted. It's funny because a lot of the controls are almost identical to the LR4. Funny thing is, I think the LR4 is nicer (in terms of luxury), although this might have been a base model XF. Also, I was very surprised to find that the B&W stereo in the XF doesn't sound quite as good as the HK Logic 7 system in the LR4. My guess is that the the B&W speakers are better, but I think the acoustics in the LR4 and the processing in the HK unit are better than the Jag. I also think the doors in the LR4 are more solid than the Jag, which creates tighter sound, since they act as speaker cabinets.
Anyway, it's a truly excellent car if anyone is in the market for a luxury/sport sedan. I'd love to drive the R-type version with 510 hp!