Speed Limiters Mandatory for New Cars: 20mph Self Enforced

In-car speed limiters stop drivers speeding. Whilst some vehicles have them as an optional extra, the EU plans to make in-car fail safes compulsory on all new vehicles from 2022[1]. Crashes will fall. Though they can be overridden, once widely used, limiters could largely replace education, engineering and enforcement further reducing societal costs. Wide-area 20mph and limiters revolutionise road safety.


[1] https://etsc.eu/meps-back-life-saving-vehicle-safety-standards-in-key-vote/

The key aim of speed limits is to protect vehicle users and especially walkers and bikers from the preventable dangers of crashes at speeds which could otherwise have fatal or maiming impact forces. 20mph is recognised as the best practice, safe speed limit for built up areas where walkers and cyclists mix with motor vehicles.

Limiters have in car cameras reading road signs or link to satellite maps. Many car makes already display the limit on their dashboard.  London buses already successfully use intelligent speed assistance (ISA) technology to restrict fuel supplies to engines to ensure drivers obey 20mph limits. Goods vehicles over 3.5 tonnes and buses are already maximum speed limited.  Many vehicles have optional speed limiters that drivers can decide to use.

Far reaching EU vehicle safety standards have been agreed at committee level requiring all new cars to be fitted with speed limiters and black box recorders. These are proposed to become law from 2022, provided they are voted through before EU elections this May. To soften the imposition of speed limiting technology the systems would – initially – include override functionality such as stepping down hard on the gas pedal. However, the internal black box recorder would track such overrides. In future insurance companies will increasingly demand that drivers stick to speed limits and do not drive aggressively.

The gold standard of road safety is 20mph limits as the default, normal speed limit for built up areas mandatorily observed by drivers with in car speed limiting technology.

Once vehicles are mandatorily speed limited, compliance is automatic at source.  Driver education on the benefits of obeying limits, speed awareness adverts, literature, courses and enforcement e.g. speed guns, cameras, community speed watch, fixed penalty notices, stop speeding signs etc become less and less necessary. Limits then can’t be abused.  There would be no enforcement lee-way allowance for drivers not realising they were speeding.  Speeds would be certain to fall.  As well as costs and pain related to the many crashes which will be prevented, costs of road safety education and enforcement drop, as do those of engineering roads for slower speeds. No more costly humps or pinch points. Questions on how best to ensure drivers do not abuse the speed limit are settled.

Fortunately, some on the road changes occur as soon as the first speed limiters are used since drivers of non-speed limited vehicles behind must go slower when the speed limited vehicles set the pace.

The UK’s Vehicle Certification Agency has said that it intends to follow EU rules. It is also unlikely that car makers will produce ‘speeding-allowed’ vehicles for the UK market.


Rod King MBE, Campaign Director of 20’s Plenty for Us said

Speed limiters being widely used are a total game changer for road safety and quality of life. This will transform compliance levels and make obsolete any previous complaints about speed limits being “ignored” by drivers. However, for a speed limit and limiter to be effective we do need the correct set of speed limits across our community road network and there is overwhelming evidence from WHO, OECD, iRAP and many more that 20mph should be the maximum speed limit where motor vehicles mix with pedestrians and cyclists. Now in anticipation of ISA we should set a national urban/village 20mph default with exceptions decided locally. It will transform the way we share the streets in our communities and provide the required conditions for a healthier and more active nation.”

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  • Rod King
    commented 2019-06-04 17:15:44 +0100
    Hi John. We think £1,000 to £2,000.
  • John Coyne
    commented 2019-06-03 15:48:22 +0100
    Any idea what it would cost now to retro-fit a speed limiter to an existing vehicle?
  • Dave H - Ode an die Freiheit (Nicht dieser Tone)
    commented 2019-04-10 08:58:34 +0100
    Speed limiters are already in use, and indeed over a decade ago Steve Whiteway of Richards (Epsom Coaches) bought a fleet of buses, to run a Tfl contract which was entirely within 30mph limits. The Euro (4?) engine management system enabled the top speed to be limited to 29.7mph +/- 1%

    The results included lower driver stress, lower fuel consumption, and less minor crash damage, all impacts on the bottom line & thus ‘noticed’ by those making key decsions.

    Rack forwards and with this system now switchable, roadside beacons and cordon-line switching have now, for several years been capping the speed of school buses entering the school to board pupils , to 10mph with one Council.

    For another the speed of refuse trucks on the wast processing sites is limited to 15mph as they cross the boundary cordon. A reverse gear 5 mph speed cap can also be applied, and a ‘break-seal’ override ensures any fast reversing has to be accounted for (reversing trucks & buses are a main and avoidable source of fatal collisions)

    Yet TfL’s London Buses are still ‘evaluating’ systems . What on Earth’s behind this seemingly contrived prevarication?
  • Malcolm Whitmore
    commented 2019-04-08 21:03:23 +0100
    Speed Limiters can hopefully be the key to open the door to beat the objectors to 20mph who claim that without effective enforcement their tax money is being wasted. Now we need to be able to instal the new limits without all the red tape and cost.