I generally buy vehicles that have 200k or more miles and keep them on average 2-4 years. I replace normal consumables but never do major repairs, I just buy a new to me vehicle. I usually have a spare as backup, in incase my daily driver craps out and I am not under the gun to replace, that way I can take my time and look for a good deal, I generally spend $500-$2000 tops
my current daily driver is a 96 Jeep Grand Cherokee Orvis Edition, only 160k, everything works, I have a 98 Subaru Legacy in the wings as backup, my last daily driver was an '81 Chevy G30 van paid $1000 drove it 3 years wouldn't pass inspection, drove it to the scrap yard and got $550 for it in scrap
The least expensive to operate vehicles I have ever owned on a cost per mile basis was a pair of 3 series BMWs, and '81 E21(320i) and an 86 E30 (325e), my most expensive vehicles per mile are my motorcycles, high cost of tires makes up any savings in fuel
2002 Toyota Tacoma with 135k miles. Commuting on the bike cuts my cost of truck ownership in about half. That's around $20k in savings. Covers the cost of the motorcycle.
I would like to see a calculation which shows that using a motorcycle to supplement or replace 4-wheel vehicle use has any cost savings benefit. The only way to make this work is to estimate gasoline savings alone, which is only a fraction of the total cost comparison. I doubt if any of us will live or ride long enough to realize $20K in savings by using a bike unless gas goes to $20/gal.
Nobody ever saved money by buying a motorcycle, but luckily that's not the purpose.