I get the same phone call every few weeks. Someone has found the car. The photos are beautiful. The seller has a binder thick as a phone book, full of receipts, and a story about how no expense was spared. They want me to come and look before they wire the money. And almost every time, before I have touched a single bolt, I already know whether the bodywork was done by someone who cares or by someone who was paid to make it shiny by Friday. You learn this from gaps. Panel gaps don't lie. People lie, paperwork lies, but the steel sits where it was put, and it tells the truth to anyone who has spent enough years putting it there.

For fifteen years I beat panels in Porto. Alfa, Lancia, the soft old Mercedes bodies, the Citroëns that were never straight from the factory to begin with. I am going to tell you what I look at, in the order I look at it, so that the next time you stand in front of a "finished" car you can read it the way I do.

Stand at the corner first, never the front

The worst thing you can do is walk up to the front of the car and admire it head-on. That is the view the seller staged for you. Go to a corner instead, crouch down so your eye is level with the swage line — the crease that runs along the side of most older bodies — and sight down the whole flank like you are aiming a rifle. You are looking for the reflection of a straight edge, a window frame, a fluorescent tube, anything with a hard line. Let that reflection travel down the door, across the gap, onto the rear quarter. If the line breaks, kinks, or goes wavy as it crosses from one panel to the next, the panels are not in plane with each other. That is either filler hiding a wave or panels that were hung without anyone bothering to align them properly.

A real restorer spends days, genuinely days, doing nothing but hanging and re-hanging doors, bonnet and bootlid until the gaps are even and the surfaces flow. A repaint shop bolts them back roughly where they came off and sprays over the evidence.

What a good gap looks like, and what a bad one is telling you

On a pre-1980 European body you are not chasing a modern 3mm laser-tight gap. These cars were hand-assembled and the factory tolerances were generous — a Giulia or a 105-series Alfa left Arese with gaps that wandered between maybe 4 and 6mm, and that is correct. What you want is consistency and taper. A door gap should be the same width top to bottom, or taper very gently and evenly. The two things that should set off alarms:

  • A gap that is tight at the top and open at the bottom (or the reverse). The door is hung wrong, or worse, the A-pillar or the sill below it has rotted and dropped, and the whole aperture has lost its shape. On unibody cars that is structural, not cosmetic.
  • A gap that is even but enormous — 8, 9, 10mm. Someone ground the door edges back to make a swollen, filler-heavy door close without binding. They cheated the fit instead of fixing it.
  • Gaps that don't match side to side. Compare the driver's door gap to the passenger's. On a properly restored car they mirror each other closely. When they don't, the shell has been pushed out of square — usually old accident damage that was pulled but never truly corrected.

Open and close the doors yourself. A door that needs a shove, or one that drops on its hinges as it swings, is telling you the hinges are worn or the pillar is soft. A door that closes with a clean single sound, not a rattle and not a slam, is hung right.

The paint thickness gauge is the most honest tool you can carry

Buy one. An electronic coating thickness gauge that reads both ferrous and non-ferrous costs around 120 to 180 dollars and it has saved my clients more money than anything else in my bag. It measures, in microns, the total thickness of everything sitting on top of the steel — primer, paint, clear, and most importantly, filler.

Factory paint on these old cars typically reads somewhere between 90 and 150 microns. A good quality respray over properly prepared steel reads maybe 150 to 250. The moment you see 400, 600, 1000 microns and climbing, you have found filler. A little filler is not a crime; even a concours restorer will skim a few tenths of a millimetre to get a panel dead flat. But filler should be a thin skim, under a couple of millimetres. When the gauge starts screaming past 1000 microns over a wide area, someone troweled body filler over rust or over a dent they couldn't be bothered to beat out.

Take readings methodically. Go panel by panel and take five or six readings on each: top, middle, bottom, around the wheel arch lips, along the lower few inches of the doors and quarters. Write them down. What you are hunting for is not one high number but a pattern. A door that reads 180, 180, 190 across the top and then 900, 1500, 2000 along the bottom edge is a door with rust or crash damage buried under a slab of filler at the bottom — exactly where these bodies rot. The lower six inches of any old European panel is where the truth lives.

Overspray is a confession

Overspray is the dusty haze of paint that lands where it shouldn't. A car that was properly stripped to bare metal and refinished has no overspray, because everything was masked or removed before painting. So when you open the door and find a fine mist of body colour on the rubber weatherstrips, on the door hinges, on the underside of the bonnet, inside the fuel filler flap, on the back of the badges — that car was painted in a hurry without disassembly. It was a blow-over, a respray done with the trim still on the car, masked with tape and newspaper rather than taken apart.

That tells you two things. First, nobody addressed what was hiding under the trim — and trim is exactly where rust starts, because trim traps water. Second, if they cut this corner, they cut others. Run your finger along the rubber seals. Check the jamb of every door where the latch sits. Look at the seatbelt mounts and the screw heads inside the boot. Original-colour paint on a screw head that should be a different shade, or paint sitting on top of a rubber grommet, is overspray. It is the single most reliable sign that a "restoration" was actually a cosmetic respray.

Read the inside of the panels, not just the outside

Anyone can make the outside of a panel shine. The backside is where the welder shows you who they are. Open the boot and look at the inner wheel arches and the boot floor seams. Open the bonnet and look at the inner wings and the slam panel. On a car that was repaired honestly you will see neat, evenly-spaced MIG welds that have been dressed back, or on the better jobs, gas-welded seams finished with lead. On a botched car you will see globby, blown-through welds, brazing where there should be steel, a thick smear of seam sealer painted over to hide a joint, or factory spot-weld patterns that simply stop and become a continuous ugly bead — the signature of a replacement panel grafted in.

Get under the car too, even if it is just on your back with a torch on the seller's driveway. Look at the sills from below, the suspension mounting points, the floor pans. Fresh underseal sprayed thick and black over everything is not a sign of care. It is a sign of concealment. Underseal is where rust goes to hide, and a recent heavy coat of it on a car being sold is a red flag, not a green one. I would rather see honest, clean, painted metal underneath, even with a few scars, than a uniform layer of fresh black goop I cannot see through.

What the wandering gaps were really telling you

Here is the thing I want you to leave with. None of these signs — the kinked reflection, the gap tight at one end, the gauge reading 1500 microns, the haze of overspray on a hinge — is, on its own, proof of disaster. But together they form a picture, and the picture is about intent. A car restored by someone who understood the body was disassembled, the rust cut out and replaced with proper steel, the panels hung and re-hung until they flowed, the filler kept to a skim, and the paint laid over honest metal. A car that was prepared to sell was masked, blown over, troweled, and shined.

The gap between those two cars is the gap between an asset and a liability, and on a six-figure car it can be forty or fifty thousand dollars of hidden work waiting for you. The good news is that the steel cannot hide it from you. You only have to learn to look. Stand at the corner, sight down the flank, carry the gauge, open everything that opens, and get underneath. The panels will not lie to you. People will. Trust the steel.