He's had a tradition of parking in handicapped spaces for a long time, so no, you can't use his illness as an excuse.
But I think I know why he did it. There are legal requirements mandating a specific number of handicapped spaces, even when few handicapped people are employed by you or visit you. So if you own the company, you are probably irked that you have to create and label all these spaces, even though they are used less than 1% of the time. Then the idea pops up: Why not use one (or even two) of your handicapped spaces as a de facto CEO spot?
That seems perfectly reasonable to me, and no actual handicapped people were harmed or even inconvenienced.
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I do find it amusing he leased a new car every six months. For those not in the know, that's the most expensive way to buy a car, ever. Even Newport Beach barons keep their cars for a year or two.
For those appalled by the ostentation of this policy, remember that a lot of good people were employed building him those cars, and selling and maintaining them. That's something people forget about the toys of rich men - they tend to create a lot of jobs, in all kinds of places.
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I don't think Steve has ever been all that green, per se. He has been into natural foods, yes, and he was a Democrat, but that doesn't make him particularly environmentally sensitive. He not only owned a SL55/63 but also a Gulfstream V jet, which is one of the most environmentally insensitive forms of transportation invented by man. I am sure the pollution from his car was completely dwarfed by his jet, which he appears to have made pretty heavy use of over the years.
What he really loves is a clean, German-styled design. That defines the SL55. There are no visually appealing environmentally sensitive cars I know of other than the Tesla Roadster. While he could have easily afforded a Tesla, I suspect its rough ride would have caused a lot of pain. The SL55 has a perfect balance of ride and handling so however bad his cancer it would always keep him as comfortable as possible under the circumstances.
D