In The Times today it says classic car prices have peaked. One of the reasons being that there are fewer "grease monkeys" to maintain them. Apparently youngsters today prefer to work on high tech. Look out for bargains as prices tumble!
I read this too. In my experience, most owners of valuable classic cars do not work on them themselves - in fact it would probably damage the value if they did. The history files, which are so important to maintain the value, should feature 'approved' or 'known' garages. I've owned some classics and I wouldn't what to do under the bonnet.
Values have gone a bit soft but it's nothing to do with home maintenance.