sober_ruski,
I am sure that you are already aware, but it is common for insurance companies to unfairly inflate their prices for vehicles which they deem to be "sports" or "high performance" types. When I checked out wikipedia's write up regarding the Prelude, it classifies the Prelude as a sport compact.
Also, when I previously went to renew my car's insurance, the broker asked me if I had made any modifications to my car that would increase its performance. Understanding this and also assuming the fact that the article on Wikipedia makes abundant references to the large variety of modifications that are availiable for the Prelude, this may be one of or the possible reason why a comparitively less expensive car may be more expensive in terms of insurance than a more expensive car.
This point is pure assumption but please indulge me. Since the Prelude is considered to be an entry level sports car which will tend to be more popular with people who are younger due to is lower cost, I would assume that since insurance companies are well known for jacking premiums up for unmarried males under age 25, and that 325i BMWs will tend to be driven much more carefully and more often by say, middle aged executives who are married with kids, that that may be another reason why the Prelude may be more expensive insurance wise.
Forgive me if I am wrong, but when I replied to your post I checked your profile and saw that it was only partially filled out with your rank only being displayed as Pte, I wrote this post in a context that I thought would be most beneficial to you. I also assumed that you are a person who is under 25, unmarried and not a corporate executive

. If I am incorrect, please disregard my advice.