Two drivers, 6 vehicles, two with engines.
My vehicle is a '95 Toyota Standard (Mini) 4x4. I got it so I could get to work no matter the weather. Wifes vehicle is a Toyota Matrix. Unlike private industry the University closes for inclement weather.
Of the other four cars two are hobby cars, the Lincoln is a donor for one of the hobby cars, the last is a van abandoned here by B-I-L which is now used as storage by Wife.
Other IC things? 40 year old Cub Cadet and ~ 35 year old lawn boy. Both are worth maintaining, or rebuilding and Zero Timing, because new replacements have been 'value engineered' into scrap.
As for the question "how much is enough", Its NEVER enough. People will rationalize and perform any 'mental gymnastic' to justify their wants. Problem is people have allowed their wants and needs to be confused. I guess this is to be expected when people allow their rational side to be jerked around by impersonal mass marketing propaganda.
Not to say I don't buy more than I need, Good Golly, I have a Restaurant Range. How many home cooks need 28k burners? I admit I look at my burner at half flame and wonder how much less efficient it is than a homeowner unit on full.
...
I place greater emphasis on Quality than Quantity. Having stated I believe some things have been 'engineered' into junk I tend to look at the used market unless there is an exigent need. I looked for a suitable range at auctions and sales for at least two years before throwing in the towel and buying new, about 20 years for a KitchenAid.
I have ~ $300 total in a 80's Craftsman Table Saw, a '60's Rockwell 9" TS, and a 50's Rockwell 4" Jointer, and tooling to use each. I could use bigger better but I don't need bigger better. And I wouldn't want a new Delta. Their made in China.
I'm not worried about economy and commerce. I have little to no choice in my consumables, Some conglomerate will get their hooks in my money either directly or by arranged consequence. Buy Halliburton Oil, money lands in U.A.E. not to mention Tax money .... On some levels thats amusing. Buy a Honda and a chunk of your money could land in the Marysville Ohio community. Buy most anything at Walmart and a chunk of the money lands in China and not a whole lot to the community. My buying used keeps the money in the community a little longer.
Ecologically buying used makes sense. Whatever it is it's already made, manufacturing costs have been covered. May be some transportation costs.
Ecologically, Using old stuff isn't as clear cut. My Cub Cadet is a mini grunt and pull machine with a mower deck slung under her belly. The Cub uses 1 ~ 1 1/4 gallons to cut ~ 1/2 acre of rough terrain, not an unreasonable fuel consumption. Takes just over an hour. A while back the Emissions Gods were eying this kind of old equipment and it had me worried, I was/am not into spending $4~$6K to replace the Cub so someone else can feel good about me burning a cup less fuel and producing maybe 10 % fewer emissions. And there is an ecological impact to producing something new.
All told where does it work out?