sources and methodology
the math, in the open.
every number on the why pro page is either a direct citation or a conservative derivation from one. we keep our methodology public because we'd rather you poke holes in it than trust us.
calculator assumptions
the interactive calculator on the why pro page uses a deliberately conservative model. three inputs, one formula, one number out.
- per-vehicle base annual maintenance
- approximates the AAA Your Driving Costs maintenance/repair/tire line items, scaled to age and mileage.
- reactive-waste avoided
- industry estimates of preventive-to-reactive savings range from 3x to 8x. the calculator uses 20% as the conservative low end of what shows up as avoided reactive cost.
- avoided diagnostic visits
- typical shop diagnostic fee. Pro's instant-recall and alert surfacing removes one per vehicle per year on average.
- pro annual price
- subtracted once from total projected savings.
your real savings depend on your vehicle, your driving, your shops, and how well you actually use Pro. the calculator is a starting point, not a guarantee.
vehicle-specific sources
AAA driver surveys and automotive service industry analyses. these are the primary sources behind the numbers on the why pro page.
One-in-Three U.S. Drivers Cannot Pay for an Unexpected Car Repair Bill
AAA Newsroom, April 2017
64 million US drivers (~1 in 3) cannot pay for an unexpected vehicle repair without going into debt. Average unexpected repair bill: $500 to $600. Only 38% could cover a $2,000 repair from savings.
Why Skipping an Oil Change Could Cost You Big
AAA Club Alliance, January 2026
Oil changes cost $40 to $100, and that price "pales in comparison to the cost of major engine repairs caused by neglect."
What Does It Cost To Own And Operate A Car
AAA Automotive
AAA Approved Auto Repair shops report 35% of drivers have skipped or delayed recommended auto service, leading to higher long-run costs.
Your Driving Costs, 2024
AAA
Annual ownership and operating cost benchmarks across vehicle segments. Used as a sanity check on our base-maintenance-spend assumptions.
Deferred Car Maintenance Trends
The Zebra
Consumer survey data on why drivers defer maintenance and what it costs them downstream.
The True Cost of Skipping Oil Changes
Sullivan Tire and Auto Service
Industry analysis: drivers who extend oil changes to twice the recommended interval typically face engine repairs 20-50x that savings within a few years.
How Preventive Maintenance Cuts Vehicle Repair Costs
Linked By Six
Summary of the preventive-to-reactive savings ratio in consumer vehicle maintenance: every $1 in preventive care typically prevents $3 to $8 in future repair cost.
How Preventative Car Maintenance Saves Money
Hi-Tech Car Care
Shop-side perspective on the long-run economics of regular preventive service.
the broader preparedness principle
these aren't cited on the why pro page itself because they're not about cars. they're here for readers who want to see the broader pattern: across federally-tracked domains, dollars spent on preparedness consistently outperform dollars spent on response.
Every $1 Invested in Disaster Mitigation Saves $6
The Pew Charitable Trusts, January 2018
Summary of the National Institute of Building Sciences "Natural Hazard Mitigation Saves: 2017 Interim Report," which analyzed 23 years of federal mitigation grants and found a 6:1 benefit-cost ratio.
Mitigation Saves Fact Sheet
FEMA, 2018
Federal summary of the NIBS Mitigation Saves research. The 6:1 ratio is broadly cited as evidence that preparedness spending outperforms reactive spending across domains.
NIBS · Mitigation Saves Research Highlighted During House Hearing
National Institute of Building Sciences
Policy context for the preparedness-to-recovery principle.
find a number we got wrong? tell us.
r/ddpc