A car is about the worst place you can put a plastic part. The dashboard can hit 70°C parked in the sun. Exterior trim soaks UV all year, freezes in winter and shakes at 130 km/h. The material you choose matters more than the printer or the settings.
The three candidates
PETG is our default for most exterior parts — tough, easy to print reliably, good chemical resistance, and it survives typical exterior use. Its weak point is sustained heat: above roughly 70°C it starts to soften, which rules it out for the hottest spots.
ABS handles more heat than PETG and is what a lot of the originals were actually moulded in. The catch is it's hard to print well — it warps, and it's weak against UV unless it's painted or coated.
ASA is ABS with the UV problem fixed. It keeps the heat resistance and gains proper outdoor weather resistance. It's what you'd print a garden fixture or an unpainted exterior part from. It's our material of choice for anything that sits in direct sun and near heat.
SHIPS 3–5 DAYS
Matching material to location
- Interior trim, cup holders, vents — ABS or ASA. These see the highest cabin heat and don't need paint to survive.
- Exterior painted trim — PETG or ASA, depending on how close to the engine and sun it lives.
- Engine bay — ASA or ABS. This is the hottest environment on the car, and PETG simply doesn't belong there. An intercooler air guide is a classic engine-bay job.
- Anything structural or load-bearing — we'll tell you when plastic is the wrong call entirely and point you toward CNC or metal instead.
Why ASA over ABS, most of the time
ASA costs a little more and prints a little slower, but it eliminates the two things that kill ABS parts outdoors: UV brittleness and long-term fading. For a part that's going to live on a car for years rather than months, that trade is almost always worth it. The full decision tree for any part is in our materials guide.
The honest caveat
None of these is a magic material. A printed part will not outlast a well-made injection-moulded original in the same location. What a good material choice does is close enough of the gap that the part earns its place — and for a part the manufacturer stopped making, "close enough to last for years" is usually the whole point. See OEM vs 3D-printed for the fuller trade-off.
Not sure which material your part needs? Send us the details and we'll tell you straight.
