The Creative Checklist for Auto Ads: Dielines, Bleed, File Formats and Proofs

The creative problems that actually delay an auto campaign are almost never about the idea. They are about a file that was built at the wrong size, exported in the wrong colour space, or handed over without the fonts. Getting the handoff right is a mechanical checklist, not a creative skill.

Why Does Auto Ad Artwork Fail at the Printer and Not at the Design Stage?

Because the design is usually fine and the file usually is not. Across 5,000+ autos and 500+ brands since 2020, the creative problems that delay an install are rarely about the concept. They are about production files.

The pattern repeats. A brand signs off on a hood design in a slide deck, the agency sends across a JPEG at 1200 pixels wide, and the print vendor now has to either upscale it into mush or ask for a source file that nobody can find because the freelance designer has moved on. That conversation costs three to five working days, which on a campaign with a fixed launch date comes out of the campaign, not out of the calendar.

What Is a Dieline and Why Does an Auto Hood Need One?

A dieline is the exact cutting and folding template for the physical surface you are printing on. For auto branding it matters more than in most print work, because an auto hood is not a flat rectangle. It is a three panel canopy with a front face and two side faces, and it curves.

Design an ad as one wide rectangle and one of two things happens. Either the artwork is squeezed to fit the real panel shape, which distorts the logo, or it is cut to fit, which is how headlines lose their last word. Neither is the printer's mistake. Both are the result of designing for a shape that does not exist.

The practical rule is simple: ask for the dieline before design starts, not after approval. A dieline should arrive as a vector template with the trim line, the bleed line, the safe area and the seam positions marked on separate locked layers, and the artwork should be built inside it at 100 percent scale.

The seams are the part that designers who have never seen a printed auto tend to miss. Where the front panel meets a side panel there is a physical fold. Text crossing that fold breaks, and a logo centred on it is destroyed. A three panel hood is genuinely three design surfaces sharing one visual system, and the legibility rules in our auto ad design guide apply to each panel separately.

The 24×18 inch and 24×6 inch sticker formats are simpler, because they are flat vinyl on a flat door panel. They still need a dieline, because the printed rectangle and the visible rectangle stop being the same thing once a sticker is squeegeed around a door edge.

How Much Bleed Do Auto Panels Actually Need?

Ten millimetres on every edge, with 25 millimetres of safe margin inside the trim line.

Bleed is the artwork you extend past the cut line so a slight misalignment in cutting does not leave a white sliver along the edge. Large format cutting on rexin and vinyl is not laser precise, and it does not need to be, as long as the file carries enough bleed to absorb the variance.

Safe margin is the opposite promise. It is the distance inside the trim within which nothing important may sit. Logos, phone numbers, QR codes and the last character of a headline all live inside the safe area or they risk being trimmed, wrapped around a door edge, or lost in a seam.

These two numbers separate a file that prints once from a file that prints twice. Artwork arriving from an external design team regularly arrives with zero bleed, because the designer built to the exact trim size. That file cannot be printed as supplied. It has to be rebuilt, and rebuilding somebody else's artwork is where new errors enter.

Which File Format Should You Send the Printer?

Print-ready PDF, exported from vector artwork, with fonts outlined and images embedded. In practice that means PDF/X-1a or PDF/X-4, and it means the file was built in Illustrator, InDesign, CorelDRAW or Affinity rather than in a presentation tool.

Vector is the point. A logo held as vector prints cleanly at any size, which matters because the same brand mark goes onto a 24×6 inch strip and a full hood in the same campaign. A logo held as a small raster image goes soft the moment it is enlarged, and on a hood it goes soft at exactly the reading distance where people actually see it.

Outline the fonts before export, or embed them fully. A PDF that references a font the print vendor does not own will silently substitute something else, and nobody notices until the proof arrives with the headline set in a default serif.

Send the layered source file alongside the PDF. Not because the printer should edit it, but because campaigns get extended, formats get added and phone numbers change. A source file kept with the campaign is the difference between a ten minute amendment and a redesign.

Should Artwork Be RGB or CMYK, and Will the Brand Colour Match?

CMYK, converted deliberately before you export, not automatically at the RIP.

Eco-solvent printing on rexin and vinyl is a four colour process. Screens are RGB and backlit, so they show saturated blues, bright greens and neon oranges that no four colour process can reproduce on a matte substrate. If you let the conversion happen automatically at the last moment, the first time anyone sees the real colour is when the fleet is already printed.

Convert early, look at the converted version, and adjust while adjusting is still free. Brand reds, deep blues and any fluorescent tone are the usual casualties. Which substrate and which ink system hold that colour through a monsoon is covered in our materials guide.

What Resolution Does a Hood Panel Need?

150 dpi at final size. Not 300, and not 72.

Print resolution advice usually comes from the world of brochures held at 30 centimetres. An auto hood is read from between five and thirty metres, in motion. At that distance 150 dpi at full scale is beyond what the eye resolves, and the substrate itself, a textured rexin, cannot hold finer detail regardless of what the file contains.

Going to 300 dpi at hood size produces a file of several hundred megabytes that is slower to transfer, slower to RIP and no better on the road. Going below 100 dpi is visible, and it is visible in the worst place, which is the logo edge and the small print of a phone number.

The check that actually matters is the source image, not the export setting. A stock photograph at 1500 pixels wide cannot become a 36 inch panel at 150 dpi no matter what the export dialog is set to. Check the largest placed image at 100 percent zoom before you build around it.

Do You Need a Physical Proof, or Is a PDF Enough?

You need a physical proof, one per format, signed before the fleet prints.

A PDF proof catches content errors: a wrong phone number, a missing offer, a typo in an outlet name. Those are worth catching and a PDF catches them cheaply. What a PDF cannot show you is what the print will look like, because a screen cannot show ink on rexin. Colour density, how the brand red actually lands, how text reads against the real texture, and whether a QR code scans from the printed surface are all physical questions.

The QR code deserves its own line. A code that scans perfectly on a screen can fail on a printed matte panel because of ink spread, contrast loss, or simply being too small. Scan it from the physical proof, with an ordinary phone, from the distance a real customer would stand. Our guide to tracking response from transit ads covers what to do with the scans once they work.

One proof per format, not per auto and not per city. On a multi-city campaign the proof is approved centrally and the approved proof file is what every city prints from. That is the control that stops artwork drifting between locations. The proof adds two to three days to a launch timeline. Budget those days rather than skipping the step, because a reprint costs more days than the proof ever will.

What Does a Complete Handoff Pack Look Like?

Send the following and the print vendor can proceed without a single clarifying email. If any item is missing, expect at least one round trip.

1. 1Print-ready CMYK PDF per format, built on the dieline at 100 percent, with bleed, fonts outlined and images embedded.
2. 2The layered source file, with linked assets packaged.
3. 3The vector logo, separately, as AI, EPS or SVG.
4. 4A one page spec sheet naming the format, the exact panel dimensions, the fleet quantity and the city.
5. 5The brand colour values as CMYK, with a note on any Pantone approximation already accepted.
6. 6A named approver with the authority to sign the physical proof, and the date by which they will.
7. 7The campaign start date the print schedule is working back from.

Item six is the one that quietly breaks timelines. A pack with everything except a person who can say yes sits still just as effectively as a pack with no files at all.

What Goes Wrong Most Often?

In rough order of how often we see it: no bleed, raster logos, RGB export, missing fonts, artwork built to a guessed panel size, text crossing a hood seam, a QR code never tested on a physical print, and a proof approved by somebody who was not authorised to approve it.

Every one of these is caught by a checklist run before the file leaves the design team. None of them is caught by looking at the design on a laptop, which is what usually happens instead. The broader pattern of budget lost to avoidable process errors is covered in our common mistakes guide. The cost of running the checklist is about twenty minutes.

The Pre-Flight Checklist

• Artwork built on the supplied dieline, at 100 percent scale
• 10 mm bleed on every edge
• Critical content 25 mm inside the trim line
• No text or logo crossing a hood seam
• CMYK, converted deliberately, brand colour reviewed after conversion
• Fonts outlined or fully embedded
• Largest placed image checked at 100 percent zoom, 150 dpi at final size
• Vector logo supplied separately as AI, EPS or SVG
• QR code scanned from a physical print, from real reading distance
• One physical proof per format, signed by a named approver
• Source file packaged and archived with the campaign

What Rates Does This Planning Sit On Top Of?

Media is ₹580 per auto per month for hood branding, ₹230 for the 24×18 inch sticker and ₹140 for the 24×6 inch strip, with metro union charges on top. Printing is one-time, at ₹250 to ₹400 per hood and ₹40 to ₹80 per vinyl sticker. Full workings are in our cost guide, and format choice is covered on our hood branding and sticker branding pages.

Nobody reprints a fleet because the design was wrong. They reprint because the file had no bleed, the logo was a JPEG, and everybody approved it on a laptop screen.