What you will actually pay at a collector car auction

The number you bid is not the number you pay. On every auction platform there is a layer of cost between the hammer and your driveway, and it is large enough to turn a good buy into a bad one without a single thing about the car changing.

This page is arithmetic. It gives away nothing about how a car should be valued — it is about what happens after you have decided what the car is worth.

The four costs stacked on top of your bid

Buyer's premium. A percentage of the winning bid, paid by you, to the auction house. This is the big one and it varies enormously by venue. Online enthusiast auctions generally sit in the low single digits and usually cap the fee at a fixed ceiling. Traditional live auction houses — the ones with a catalogue and a tent — commonly charge several times that, and often tier it, so the rate steps down above a certain hammer price.

Never assume. Every venue publishes its current fee schedule, and the rates change. Read the specific terms for the specific sale before you bid, because a premium you guessed at is the most expensive guess in this process.

Where the two biggest enthusiast platforms sit, as of October 2026. Both are widely reported at 5% of the winning bid, with a $250 minimum and a $7,500 cap — Bring a Trailer and Cars & Bids alike, the latter having raised its fee from 4.5% to match. Motorcycles and some other categories are charged at a different, higher rate on at least one of them.

Treat those figures as a starting point and not as gospel: both platforms changed their structure recently, stale numbers are still being repeated across the web, and the only authoritative source is the venue's own fee page on the day you bid. The figures above come from press and secondary reporting because neither platform permits automated reading of its own terms — which is itself a reason to go and look yourself.

What the cap means in practice: at 5% with a $7,500 ceiling, the fee stops growing once the winning bid passes $150,000. Below that you are paying the full percentage; above it, the effective rate falls the more you spend.

Sales tax and registration. Charged by the state where you will register the car, not where the car is. Many states tax the full purchase price including the premium. A few have no sales tax at all. On a five-figure car this is frequently larger than the buyer's premium.

Transport. Open transport is cheaper and exposes the car to weather and road debris. Enclosed is typically a substantial premium over open and is the only sensible choice for fresh paint or anything you would be upset to see stone-chipped. Cross-country costs more than regional, and a car that does not run or roll costs more again, because it needs a winch and sometimes two people.

Immediate recommissioning. The work the car needs before you can actually use it, as opposed to the work it needs eventually. Fluids, belts, tyres that are date-expired regardless of tread, a battery, a brake system flush on anything that has sat. Budget for this separately from restoration wishes — it is not optional and it lands in the first month.

Working backwards from your real budget

Most people set a budget, bid up to it, and then discover the extras. Do it the other way around. Start with the total you can spend, remove the fixed costs, then divide out the percentage costs:

max bid  =  (all-in budget − transport − recommissioning)
            ───────────────────────────────────────────────
                  1 + premium rate + tax rate

A worked example. Say you can spend $50,000 all-in, you are looking at a venue charging a 5% buyer's premium, your state charges 7% sales tax, enclosed transport will be $1,800, and you have set aside $2,500 for recommissioning:

numerator    50,000 − 1,800 − 2,500        = 45,700
denominator  1 + 0.05 + 0.07               =   1.12
max bid      45,700 / 1.12                 ≈ 40,804

Your ceiling is roughly $40,800, not $50,000. If you had bid to your budget you would have gone over by more than nine thousand dollars — eighteen per cent — and you would not have found out until the invoice arrived.

Run this before the auction opens, write the number down, and treat it as the wall. The entire design of a live auction is to make you move a number you set calmly while you are no longer calm.

Where the cap matters

On venues that cap the buyer's premium, the effective rate falls as the price rises. A capped fee on an expensive car can work out to a fraction of a per cent, while on a cheap car the minimum fee can be a painful share of the purchase. Check both ends of the schedule: the floor hurts on inexpensive cars and the ceiling helps on expensive ones, and the percentage in the headline describes neither.

The fee you cannot see

Reserve. If a sale is reserve-not-met, nothing happens and you have spent nothing — but you have also spent the time, and sometimes a deposit hold. More usefully: a car that has failed to meet reserve repeatedly across several sales is telling you something, and what it is telling you is rarely about the reserve.