Sounds like an excellent plan to me. Old Japanese car values are only going one way for nice examples of desirable models like your 200sx
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This sits in my garage for hi-days and holidays and if I had to choose it certainly wouldn't be the M3 that'd be staying. (The old Honda is a darned sight cheaper to own into the bargain).
Coming back on-topic.....another vote for solar panels - for 7-8 months of the year they make a huge difference.
Our 4kwh system was installed 7 years ago with a decent FiT rate. It paid for itself within ~4.5 years, so everything generated and used is free electricity....and the government also give us ~£900/year through the FiT.