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Should you upgrade your headlight bulbs?

Martynn's tips

Martynn Randall is technical editor at Haynes and has been with us for approaching 30 years. He's written more than 60 Haynes publications and has owned more than 85 cars and 60 motorbikes... so far!

Modern car headlights are incredibly bright. Indeed, some may say that they’re too bright, but they definitely allow you to see further ahead than ever before.

But what if you have a slightly older car that doesn’t have the modern HID/LED/laser lighting systems of today’s machines? Older halogen bulbs can make you feel like you’re driving along dark roads behind a couple of flickering candles. And if something comes the other way with super-bright LED headlights, you can be completely blinded for a few seconds, partly because your own lights don’t have a bright enough beam pattern to counteract the oncoming glare.

However, you can easily make a difference by upgrading the bulbs on your car, to make night driving easier.

Car headlight with reflector

How to fit brighter bulbs and stay legal

It is well worth upgrading your headlight bulbs. Independent tests have shown that aftermarket bulbs can increase light by around 130%. Not only that, but brighter bulbs means less eye strain, which means less tiredness, so you’ll be safer.

The only way to upgrade your old halogen headlights is to simply replace the standard factory bulbs with brighter aftermarket ones, such as Osram Nightbreakers, or Philips RacingVision bulbs.

Kuga bulb

Where does the law stand on HID and LED headlight bulbs?

Using LED or HID bulbs, even with a conversion kit, is illegal if your car has H4 or H7 halogen bulbs. If you do fit them, you’ll be leaving yourself open to a fine, and your car will fail its MoT test. This is because halogen lights require a reflector (the shiny silver bit at the back wall of your headlight unit) to focus their beam in the right direction.

However, because LED and HID bulbs need a focusing lens ahead of them instead of a reflector behind, fitting them to a traditional halogen headlight unit means they’ll end up being far too bright, and their beams will be widely dispersed, so they’ll end up blinding other drivers. In cars fitted with HID/LED bulbs, the actual glass front of the headlight unit is often the lens that’s used to focus their beam in the correct direction. Hence, they’re illegal in cars without this type of headlight unit.

Furthermore, a car with an HID bulb fitted is also required to have a self-levelling system, or the bulb could end up illuminating the sky, not the road.

Additionally, HID bulbs are larger than halogen bulbs due to the ignitor unit attached to their back. This makes them incompatible with standard car headlights. Yes, conversion kits are available, but the quality of these is patchy at best, and the bulbs are still illegal afterwards.

However, as with any rule, there are exceptions. If the car you plan to fit the LED bulbs to was built before 1 April, 1986, then you’re okay to fit LED bulbs. Such cars are not required to use type approved ‘e’-marked headlights, so fitting an LED bulb breaks no laws.

Cloudy lights

How to fix foggy headlights

Of course, it doesn’t matter how bright your car’s bulbs are if its headlight lenses are dirty and foggy, because this will severely restrict the amount of light generated. So, it make sense to keep your headlights clean, and if they’re showing sign of becoming fogged up through age, then it’s worth restoring them.

We’ve put together a guide on how to restore your headlights, but in essence you need to clean them, then sand and polish them.

Halogen bulbs are cheap and legal

The reality is pretty clear – if your car has halogen bulbs as standard, then the best way to upgrade the amount and colour of light they produce is to upgrade to aftermarket halogen bulbs.

Anything else is going to be either enormously expensive or will lead to your vehicle failing its MoT.

Car in woods