Why would you pay to rent a car when you already own a car? Is it on its last legs or something? If so, then fine, but don't do it just to save some mileage.
Can we see some math on this? Assuming you will wind up paying roughly the same amount on gas for one's own car vs. a rental car, what is the math on own car's depreciation, maintenance and repairs vs. a rental car?
I'm assuming for the own car scenario, roughly 1600 miles one direction from Arizona to Ohio, and assuming $0.10** per mile of driving costs excluding gas (i.e., only depreciation and maintenance/repairs for say a used 2003 Honda Civic or a Toyota Corolla), the round trip costs $320, excluding gas.
My math suggests that for every trip that exceeds one way 600 miles, you are better off renting a car at about $120/week. I see rates at my local Enterprise at about $95/week for an economy rental for a week, which works out just great for gas mileage. Be sure to pressurize the tires of your rental car to whatever feels safe (I go usually 10% higher than rated pressure) to may be extract a little more gas mileage.
**Assuming $500 in depreciation every 10,000 miles, $500 tires per 50,000 miles, oil, filter, wipers etc. $50 per 5000 miles, $300 in other miscellaneous maintenance/repairs every 10,000 miles. It's possible that you can drive for a lot less than $0.10/mile, but if so, I'd love to know how.
Depreciation seems odd to include in this comparison, unless you're also going to include vehicle registration, insurance, and the cost of your driver's license. Your car is going to depreciate
regardless of whether you take it on a road trip or not. Or maybe newer cars are different?
*does research* KBB.com says:
2015 Corolla 500 mi: $17,335 (excellent condition)
2003 Corolla 100000 mi: 5,564 (VG condition)
2003 Corolla 120000 mi: $4,868 (VG condition)
1996 Corolla 180000 mi: $1,294 (good condition)
1996 Corolla 250000 mi: $1,270 (good condition)
It appears that a newer car depreciates per mileage ($348/10k in this case). BUT. The older Corolla doesn't. So I guess it depends.
Here's what I get when I do your math for my car, a 1995 Honda Civic: $0.038/mile.
We bought it for $2k. If it depreciated $500 every 10k miles, it should be paying ME :P . And tires are cheaper than your quote, and oil is cheaper than your quote....I just priced tires (I need a set): I can get brand new 90k mile warranted Michelins for ~$300 (including tax). Almost all the national auto parts chains periodically run specials for 5 qt. + filter = ~$20, which is almost
two oil changes.
So when I run the numbers for my car, it costs:
Depreciation: $0/10k -- $0.000/mile
Tires: $33.33/10k -- $0.033
Maintenance: $50/10k -- $0.005
Repairs: $300/10k -- $0.03
Total: $383.33/10k -- $0.0383/mile
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TL;DR: New cars are expensive. Rental cars are also expensive.
