Grand Prix implies fast action (movement of camera work, not the cars). And that, in turn, requires high bitrate to avoid block artifacts.
If you want to break it up across a pair of 1-hour DVDs, that would work well. Use XP mode.
However, if you do not want to break up the content across spanning discs, then go for the 352x576 with the highest available bitrate. FR170 is always safely in the 352x576 + good bitrate range, and that runs just shy of 3 hours. Use FR170 mode.
And if you're interested....
The switchover from 720x576 to 352x576 varies slightly from model to model. On my NTSC JVC DR-M100 recorder, that happens at either FR160 or FR165. I forget exactly -- really need to make myself a note card.
If you want to spend some time testing the exact perfect settings, record a quick segment at everything from FR150 to FR170 on a DVD-RW. Finalize, then put in the computer, and use Gspot to see what's what.
You NEVER want to use 720x576 beyond 2 hours (120 minutes, FR120, SP mode), and even 2 hours is pushing what's acceptable. Remember that most pre-HD broadcasts, as well as most consumer recording formats (like VHS) were closer to 352x576 (or 352x480 for NTSC) than they were to the Full D1 specs. Related topic: Is SP MODE the Best DVD Recorder Mode? (NO!)
Hope that answers you.