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Is an LPG Conversion Legal in the UK?

Conditional

Running a car on LPG (autogas) is legal in the UK as long as the system is fitted competently, DVLA is told so the fuel type is recorded, and your insurer knows. Safety of the tank and pipework is the main condition.

Why?

An LPG conversion adds a gas tank and injection system alongside the petrol one, and it is a long-established, legal way to cut fuel costs. Because it changes the recorded fuel, you should tell DVLA so the V5C reflects that the car now runs on gas as well as petrol.

The real risk is safety, so the work should be done by a competent installer working to the recognised LPG standard - a properly mounted, leak-free tank and correctly routed pipework. The MOT and any inspection will look at the installation's condition, and a badly done conversion is both dangerous and a fail.

Tell your insurer as well, since it is a modification. With an approved install, the paperwork updated and cover in place, LPG is one of the more routine and accepted conversions on UK roads.

What decides if it's legal

  • Have it fitted by a competent, approved LPG installer.
  • Tell DVLA so the fuel type on the V5C shows gas/petrol.
  • Tell your insurer about the conversion.
  • The MOT checks the installation for leaks and secure mounting.

Does it depend on your car?

Tank size and where it fits (boot well or underslung) vary by car, but the safety-install, DVLA and insurer duties are identical across all of them.

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Sources

This page is general guidance, not legal advice, on the rules in the UK for LPG conversion. The detail varies by exact vehicle and changes over time - confirm with your insurer and the latest DVSA and GOV.UK guidance before modifying.