Creating a roof spoiler

A bit of matte black paint and it’s done!:

Done sideview


Done rearview

These pictures were shot just before a 500 km trip, I finished the spoiler just in time.
I did secure the spoiler with a bit of tape, I didn’t want to risk loosing it after all this work!

Secured with tape


The trip went to Budel, the greatest beetle meeting in the Netherlands:

Budel 2010

The spoiler did good on the trip, it didn’t move an inch. During the trip it started to rain a little, and the rear window stayed totally dry! Apparantly the spoiler is doing something. It’s a pitty that it’s so hard to determine if it really makes a difference in drag. The car felt stable at high speeds, but it also was the first time I drove such a distance with my Kamei spoiler (yeah, I know, never change two things at once..).
I don’t know if the fuel consumption is less either, I don’t have data of the past year.

I did a measurement later. The fuel consumption was 1 litre on 13 kilometers. Which is quite good considering I like to rev the (Alfa Romeo) engine, and it was meaured while driving stretches of highway and city driving combined.

Now, I going to try to produce this spoiler…so stay tuned..



  1. That sounds like a vortex generator , which may induce more drag than it reduces. My understanding of the roof spoiler is to provide a sharper cutoff to the airflow to reduce some of the drag caused by air partially detaching along the steeper back slope. By detaching the air completely you still have the full drag of the entire frontal area.

    • No, I don’t think it’s like a vortex generator. I think vortex generators are more for directing airflow to a rear spoiler.
      It works more like a kammback. See:
      The angle of the rear of a beetle is not good for aerodynamics. A long sloping rear or a cut-off rear (like a kammback) is better.
      But this spoiler acts like the rear is cut-off just behind the spoiler.

  2. I too am wanting a spoiler. I am redoing a 72 sb. Were you successful in producing more spoilers?

  3. Hello Gerrelt,
    sent you a request for your roof spoiler. Hopefully you will still produce them. Looking forward to you reply


  4. Hi Gerrelt , can you give the price about your roof spoiler please ? possible to get it in full carbon fabric ?

  5. Hi! Interested in buying a spoiler for my 1303s 1973. Would appreciate information about price and shipping etc. greetings from sweden, thanks in advance.

  6. Hi Gerrelt
    I am all so Interested in buying a spoiler for my 1303s 1973. Would appreciate information about price and shipping etc. greetings from Denmark, thanks in advance.
    Kent 🙂

  7. I would like to order one of your rear spoilers. What is the price with shipping to the United States (Georgia)?

  8. Hi Gerrelt

    I like to order one of these spoiler for my Dad 1970 VW Bug. the rear window has a defroster in it! How much and can I get one real quick? flying to California on the 18th of November

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