Short answer: physically yes — the new film will stick to the old one. Wise answer: usually no, and here is why, plus the situations where layering actually makes sense.

1. What happens when you layer

Vinyl sticks to vinyl, so a second layer will hold. The problems are hidden underneath:

• Contours telegraph through. Every edge, scratch, seam and piece of dirt under the old wrap shows through the new layer — you are laminating in the old car's imperfections.
• Removal becomes a nightmare. Two layers of adhesive have to come off together; the old film can tear and leave both adhesives behind, and removal heat now has to penetrate two films.
• Warranty and lifespan get murky. Most films are rated for clean, factory-paint application. A layered install lives outside that assumption, and nobody's product literature covers it.
• Edges and channels double up. Thicker corners mean lift risk at the very places wraps fail first.

2. When layering can be acceptable

• A smooth, well-maintained PPF or clear bra layer underneath a colour change, where the base is flat and fully adhered.
• Temporary colour over a factory-clear-coated area you plan to strip soon.
• Small accents where the old film is in perfect shape — never over damaged vinyl.

3. The safer route

If the old wrap is coming off anyway, remove it first. A clean removal leaves you with the surface the new film was designed for: bare, factory-painted, properly prepped metal. The removal guide shows the heat-and-peel method that protects paint. It adds an afternoon to the job and removes an entire class of future problems.

4. When you decide to layer anyway

1. Clean the old film thoroughly; any dirt becomes a permanent bump.
2. Check every edge and seam for lifting — fix or trim before layering.
3. Sand down nothing; you cannot abrade vinyl safely.
4. Keep the old layer's age in mind: if it is near the end of its rated life, replace it instead of burying it.

Bottom line

Layering works in the short term and costs you in the long term. For a full-car colour change, removing the old wrap first is cheaper than a second removal later. And if the old wrap is tired, the honest move is a fresh start — new film, clean paint, rated lifespan intact.