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Class B Campervan Fuel Security (Ram ProMaster, Ford Transit & Sprinter)

July 2026 6 min read

Estimated read time: 6 minutes

Class B van life is booming — and it puts your rig in exactly the places where fuel security matters most: crowded trailhead lots, overnight street parking, big-city stopovers, and remote dispersed campsites. Yet almost nobody makes a purpose-built fuel-security product for the Ram ProMaster, Ford Transit, and Mercedes Sprinter platforms that most camper vans are built on.

Why campervans are uniquely exposed

Your van is your home, your vehicle, and often your daily driver. That means it sits unattended in far more varied — and riskier — places than a big coach that only moves a few times a year. On diesel Sprinters and Transits especially, the filler also sits right next to the DEF cap, doubling the number of openings someone can tamper with.

  • Street parking: Your fuel fill is at sidewalk height, in public, all night.
  • Trailheads: You are gone for hours on a hike while the van sits alone.
  • Diesel resale value: Sprinter/Transit diesel is a tempting, easy grab.
  • DEF contamination: The wrong fluid in a DEF tank means a very expensive repair.

Modern Class B camper van parked at a mountain overlook showing the fuel door area

Why a factory fuel door isn't enough

Cargo-van fuel doors are thin, unlocked, and easy to pop. They keep rain off the cap — that's it. They offer zero theft deterrence and no protection against someone deliberately fouling your fuel or DEF. A locking fuel cap alone helps, but a full locking door is the stronger, cleaner solution.

The van-friendly solution

The RV Fuel Vault is a heavy-duty, keyed locking fuel door that bolts on without cutting or drilling. For camper vans it delivers three things that matter on the road:

  1. A real lock that stops opportunistic siphoning and tampering while you're parked or hiking.
  2. Contamination defense — sealing the filler area against water, grime, and deliberate fouling.
  3. A finished look that suits a nicely built van without screaming "expensive rig inside."

What about dual openings?

Diesel vans with a separate DEF fill benefit from a 2-pack, which ships keyed alike — one key opens both the fuel and DEF doors. If you later add an auxiliary tank for extended boondocking, additional doors can be keyed to match your existing set (just email [email protected]).

Bottom line

Van life means parking in public, often overnight, often alone. Your fuel filler shouldn't be the one part of your build left unlocked. Confirm fitment for your ProMaster, Transit, or Sprinter with the fitment finder and lock it down.