Almost everyone facing this decision runs the same comparison, and it is the wrong one.
Repair cost versus car value. “A $4,000 repair on a car worth $9,000? That’s madness.”
It sounds like sound reasoning. It is not, because the car’s value is not money you have. It is money you would receive if you sold it — and you would immediately spend considerably more than that replacing it.
The comparison that actually answers the question is cost per month to keep this car against cost per month to replace it. Run it that way and the arithmetic usually looks very different.
The numbers, side by side
Say the car needs $4,000 of work, and doing it buys three more years of ordinary service.
| Option | Cost per month |
|---|---|
| A $4,000 repair, spread over 36 more months | $111 |
| Average used-car payment, Q2 2026 | $542 |
| Average new-car payment, Q2 2026 | $765 |
| Total cost of running a new vehicle, AAA 2026 | $1,072 |
(Payment figures: Experian State of the Automotive Finance Market, Q2 2026 — used vehicles averaged $542/month on a $27,852 loan at 11.19% over 67.9 months; new vehicles $765/month on a $43,610 loan at 6.35% over 69.5 months. Running cost: AAA’s Your Driving Costs 2026, $12,863 a year at 15,000 miles annually. Your figures will differ — substitute your own.)
A $4,000 repair is roughly a fifth of the average used-car payment. Even a $6,000 repair, spread over four more years, comes to $125 a month.
That is the shape of the answer, and it holds across most versions of this decision.
The costs of switching that never make the spreadsheet
Three of them, and together they are substantial.
Sales tax. In Kenmore the combined sales tax rate is 10.4%, and Washington adds a further 0.3% motor vehicle sales tax on top. On a replacement at the average used-car loan amount, that is roughly $3,000 handed over on day one — before you have driven anywhere, and in exchange for nothing mechanical.
Depreciation on the replacement. AAA puts depreciation on a new vehicle at $4,422 a year — about $368 a month, and by some distance the largest line in the cost of owning one.
Here is the thing worth sitting with: your 100,000-mile car has already finished depreciating. That is not a consolation prize, it is the single biggest financial advantage it has, and it is not something you can buy. Every replacement restarts that clock. At $4,422 a year, a new car loses more value annually than most single repairs on your existing one cost.
The unknown. You are trading a car whose faults you know for one whose faults you do not. A pre-purchase inspection narrows that, but it does not eliminate it. The devil you know has real value, and it never appears in the comparison.
Why 100,000 miles is not the milestone people think
Two bits of context.
First, keeping a car this long is now completely ordinary. S&P Global Mobility puts the average age of a light vehicle on US roads at 12.8 years, and the average passenger car at 14.5 years. The fleet keeps getting older because new and used prices keep people in what they already own. You are not being eccentric; you are being typical.
Second, and more useful: at 100,000 miles the engine is usually the healthiest part of a German car.
These engines were designed around sustained high-speed running. A well-maintained European six or four at 100,000 miles is generally not near the end of anything. What actually decides whether the car is worth keeping is everything around the engine — cooling system plastics, rubber hoses and bushings, electrical connectors, suspension components, the electronics.
And that peripheral hardware ages on a calendar, not an odometer. A twelve-year-old car with 70,000 miles can be in worse shape than a seven-year-old car with 120,000.
Which means the honest answer to “is 100,000 miles too many?” is that mileage is the wrong question. Condition is the question, and condition has to be looked at rather than guessed.
What actually makes a car not worth keeping
We are a repair shop, so weigh this section accordingly — and then read it, because there are real cases where replacing is clearly right and we will say so.
- Structural rust or flood damage. Not a repair decision. Structural corrosion and water-damaged wiring are open-ended problems, and a car with either is not worth investing in.
- A cascade, not a single item. One $4,000 repair on an otherwise sound car is usually good value. A $4,000 repair on a car that also needs suspension, an exhaust, tires, a cooling system and has two warning lights is a different situation. The test is whether you are looking at one item or a list, and whether the list is longer than the last time you looked.
- Unreliability that costs you elsewhere. If the car has stranded you, if you have missed work over it, if you are paying for towing and rentals, those costs are real even though they never appear on an invoice. A cheap car you cannot depend on is not cheap.
- Your needs changed. A new child, a much longer commute, something you now need to tow. Fixing a car that no longer suits your life is solving the wrong problem.
- Safety hardware a generation behind, on a high-mileage driver. If you do a great many freeway miles and your car predates automatic emergency braking, that is a legitimate reason to move on that has nothing to do with whether the car runs.
- You do not like it any more. Underrated, and perfectly valid. Nobody should spend $4,000 keeping a car they have stopped enjoying.
And one case where we would tell you to stop spending regardless of the arithmetic: when every visit produces a new problem and nothing ever gets ahead of it. Some cars are simply used up. A shop that cannot tell you that is not being straight with you.
How to make the decision properly
The mistake is deciding on the strength of one repair quote. One quote tells you about one repair — it tells you nothing about what the next two years look like, which is the actual question.
- Get a condition report with a priced 24-month forecast, not a single quote. What is urgent, what is coming, what it will cost, in what order. That converts an anxious decision into an arithmetic one.
- Convert both options to cost per month. Repair total divided by the months it buys you, against the real monthly cost of the replacement.
- Add the switching costs. Sales tax at 10.4% plus the state’s 0.3% motor vehicle tax, registration, and the change in your insurance premium. Those are part of the replacement cost even though nobody quotes them.
- Count the depreciation you would restart. $4,422 a year on a new vehicle, per AAA. Your current car is not doing that any more.
- Then decide — and notice that “keep it another two years while I save” is a legitimate third option that the keep-or-replace framing hides.
Frequently asked questions
Is 100,000 miles a lot for a European car?
Not in itself. These engines were designed for sustained high-speed running, and a well-maintained one is generally not near the end of anything at 100,000 miles. What decides the car’s future is the condition of the systems around the engine — cooling, suspension, electrical, rubber and plastic components — and those age on a calendar rather than an odometer. A twelve-year-old car with 70,000 miles can be in worse condition than a seven-year-old car with 120,000.
Should I repair my car or replace it?
Compare cost per month, not repair cost against the car’s value. A $4,000 repair that buys three more years is about $111 a month. The average used-car payment in Q2 2026 was $542 a month and the average new-car payment $765, with AAA putting the all-in cost of running a new vehicle at $12,863 a year. Then add the switching costs — in Kenmore, sales tax alone is 10.4% plus Washington’s 0.3% motor vehicle tax.
When is a car genuinely not worth repairing?
Structural rust or flood damage, effectively always. Beyond that, the test is whether you are looking at a single item or a growing list — one significant repair on an otherwise sound car is usually good value, while a repair on a car that also needs four other things is a different decision. Unreliability that costs you in towing, rentals or missed work counts too, even though it never appears on an invoice.
How much does it cost to own a car per year?
AAA’s Your Driving Costs 2026 puts the average for a new vehicle at $12,863 a year, or about $1,072 a month, at 15,000 miles annually. The largest single component is depreciation at $4,422 a year — which is the line a paid-off, higher-mileage car has already stopped paying.
Is it normal to keep a car past 100,000 miles?
Very. S&P Global Mobility puts the average age of a light vehicle on US roads at 12.8 years and the average passenger car at 14.5 years, both records. High new and used prices are keeping people in the vehicles they already own.
Get the two-year picture before you decide
The useful appointment here is not a repair. It is a full condition assessment with a priced forecast of the next 24 months, so you can put a real monthly number against the car you have and compare it to the one you are considering.
Advanced European Service in Kenmore works on Alfa Romeo, Audi, BMW, Fiat, Jaguar, Land Rover, Maserati, Mercedes-Benz, MINI, Porsche, Smart, Volkswagen and Volvo. We photograph what we find, separate urgent from upcoming, and quote before we work — with a 2-year/24,000-mile warranty. And if the answer is that your car has had enough, we will tell you that too.
Call 425-587-8479 or book online. 17511 68th Ave NE A, Kenmore, WA 98028.