10:1 compression ratio... Likely no, the engine will most likely retard the timing to prevent damage, at 10:1 the compression really isn't the reason for needing premium it's likely an advance timing curve. That being said, you will almost certainty loose power and efficiency and cause increased carbon build up(Which can lead to mechanical issues). Chances are any money saved at the pump will bite you in losed efficiency so you'll likely end up costing yourself more money in the end. Manufacturer's place those recommendations there for a reason... It doesn't move cars to require high grade fuel so you know they aren't doing it just for shits and giggles.
Search Chrysler Crossfire Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Chrysler Crossfire Experts