Year by year the numbers got worse and worse on our aging fleet. It's why I added 2 new trucks over the last 2 years. The warranty's haven't saved me anything on the new trucks because nothing breaks and thats what I love about them.
The older trucks I wouldn't do % math as to many variables and base trucks cost a lot less than loaded trucks. My 2 new trucks cost me $60,000 and $65,000 each (we are talking fully loaded ram 4500s). My used trucks cost me $8,000 89 gmc 3500 dump purchased 2003, $10,000 99 ram 1500 quad short bed purchased 2003, $14,000 98 ram quad cap long bed purchased 2002, and $20,000 99 ram 3500 quad cab dump purchased 2005. I think its safe to say repairs and tires they average about 1 dollar per mile driven on bad years and closer to 50 cents per mile overall. All 4 of them cost me around 20k each since iv owned them. Transmissions can be upwards of $3000. Rear ends used your still looking at $1200 to $1500. Transfer case on the 4wd 99 ram 3500 that was rude came in just over $4000. Fuel injector pump for diesels close to $3000 a pop. My 89 gmc costs me the least at around $2000 a year on average but we also only drive it about 2000 miles. I don't think the issue is so much warranty expiring to ages but the miles on the trucks when you got em. I found around 80000 miles the trucks show their age and begin to break more frequently around 100000 miles things get bad and around 125000 miles its just plain ugly. It was when my average truck had 140000 miles that I snapped and figured id be better off with payments. And it is nice not being so close with my mechanic.