Leave Headlights Always On?

Are there any pros and cons to leaving the headlights always on? I just bought a Prius 2012 III and the headlights automatically turn off after leaving the car after 30 seconds, but it doesn't have the auto-on headlights, so I was just wondering if keeping them on all the time is a good or bad idea...

I'm curious to know what the pros think about this as well.

Leaving the lights on will cause a very slight MPG penalty. I believe it is worth the safety advantage, so left them turned on for the three years I had my 2010. The household's old non-hybrid with auto-shutoff has had its lights left on for 15 years / 165k miles, with few bulb replacements needed.

Your 2012 also has a DRL (daytime running lights) choice. That is also a valid daytime 'lights on' choice, and slashes the already small MPG cost. This is the mode I now use. The only downsides to using DRL are that it is no longer 'set and forget', as you must still switch to regular lights at night. And it doesn't have the taillights turned on when entering darkened tunnels in daylight.

The regular headlight's sharp cutoff line also let me put a mark on the garage wall to indicate when the car is in far enough to just clear the garage door. This doesn't work with the DRL.

HID lamps wear out sooner. DRL are a good way to go if you have HIDs. DRLs on my C shut off with the car.

^^ 2010-2012 Prius models don't have factory HIDs, so this is not an issue on unmodified cars.

Awesome, thanks for all the feedback!

All headlamps will die sooner if left on constantly. HIDs aren't any worse in this department, only they cost a LOT more to replace.

Tom

Mine have been on for 98,000 miles. Every 5000 miles my mechanic turns them off durring the oil change and I turn them back on.

Just my 2 cents worth on a GenI prius, my 2002 owners manual states that the DRL are at 80% compared to Headlights. First two weeks I had the car I got pulled over 3 different times for driving without the headlights on, ie no tail lights.

When my wife was without her car due to an accident, she always drove with the headlights off as well and was pulled over a couple times as well. So I just turned the headlights on and left it that way.

If in the garage, or within 10feet of the house and its dark out, I can tell a difference between DRL and Headlights, but on the open road, really couldn't tell a difference..

^^ DRLs (daytime running lights) at night is a violation, and any tickets are well deserved. They were never intended for that use. The pattern is wrong for night use, and on the new LED version on the 2012s is also completely useless to the driver at night. And all the other required night lighting on the back and sides is turned off.

The Prius is a very small car. The Magnetic Gray for instance is almost invisible at dusk. I leave my lights on always.
May save your life someday.

I turned the lights on when I picked up my 2005, and they stayed on for 7 years -- other than the mechanic turning them off during regular maintenance, as JimboPalmer noted above. The car did not have DRLs. I'd done the same thing on my three previous cars.

My 2012 has the auto on/off lights and DRLs, which I'm learning to enjoy. But if I didn't have them, I'd just leave the lights on.

BTW, do not do what a guy I knew a long time ago did: He not only turned his lights on, he turned on the high beams and left them there. I don't know why he never got a ticket. But he got really mad at me when I borrowed his car once and turned the low beams on.

Various colors and lighting conditions can make it difficult to see any type of car in daylight, so I agree with leaving the lights on. DRLs cover the front (the most important direction), regular lights cover all around.

But Prius' size is not an issue. It isn't 'a very small car', it has the largest visual cross-section of any car my household has ever owned. It is much larger than my old Honda Accord it replaced, and is even slightly taller and wider than my Subaru GT Wagon, really just an Outback with a bit less ground clearance and no roof extension.

The Prius has DRLs but no auto headlamps?

No wonder why I see so many Prii with just DRLs on at night!

Mine is a 2010.
I leave my lights on at all times, unless for some reason I specifically want them to be off, and the car to be on, which is almost always when the vehicle is parked.
Yes. Your headlamps will burn out sooner.
They're easy to replace, and fairly cheap.

I don't know if anybody has tried to calcuguess the mileage penalty for leaving lights illuminated, but I doubt that it's really measureable above the noise.
For me, it doesn't matter.
I ride motorcycles, so to me headlamps are kinda important.

Priuses are bigger than motorcycles, but they're still a small car.
Yeah, Yeah....I know.
There's some pucker-butt out there that's struggling furiously to get their flame thrower lit because the Prius is classified as a mid-sized car, but that's based on interior volume.
Dimensionally, it's about the same size as a Corolla, and IIRC their curb weights are within a Thanksgiving dinner of each other.
If you think it's big, then it's big.
I think it's small, so it's small.
Life is like that for many things.

So yeah. I leave the lights on.
If it were legal to do so, I'd put modulators in them.
Just about every other day I hear grumblings in this forum about how many morons there are on the road.
I want to do as much as I can to help cell phone queens and GPS jocks notice that I'm on the road too.

I am glad that i found this topic. Thanks for all the great input. I have a 2003 and a 2010 Prius and wondered why toyota did not install automatic headlights, a simple photo sensor would do the job. The thing I dislike with leaving the lights on with my 2010 is that I have to manually change the display brightness between day and night driving. my two cents.

Yeah....I know.
The Prius is a great car, but some of the ergonomic feaux-pas in my beloved G3 leave me scratching my head in wonder.....

You wanna know the funny part?
IIRC, the photocell for auto-on lights is almost certainly already installed in the car. I didn't look under the grey cover on the dash, but I'll betcha it's there...installed and wired.

It beats me why the G3, which prides itself on being on technology's cutting edge, won't enable a feature that I've enjoyed in all of my GMs for the last decade. That, and a proper battery management circuit....oh...and retained power for aux circuits...and....

I'm no big fan of government stepping in and telling the OEMs how they should configure the electronics in their cars (which is probably why some OUTCONUS G3's have auto headlamps) but I kinda like the idea of headlamps winking on when it gets dark. I also like the fact that this feature is user-defeatable like (*cough!! Cough!!!*) the traction and stability controls in a properly equipped car.


You'd be AMAZED at how many cars I see after sundown plodding their way home sans headlights.

I assume you are reffering to my post above you. While i fully see your point and agree with you on the laws etc, imo your post wasn't really neccesary if it was aimed at me. I was merely making the comment that on my 2002, it is very easy to drive at night with just DRL. And for that fact, i leave the headlights on for my safety as well as for the other drivers at night.

Except for the dash lights dimming, and a little green light that comes on, imo it is very easy to FORGET that your headlights are actually off thus you drive without your headlights on.

You might want to rephrase this statement. I assume you mean that it is easy to accidentally not turn on your headlamps, but it reads like you think it's a good idea to drive at night without headlamps, and in fact is easy to do.

Tom

Good point! Thanks Tom!!

I rephrased my comment, so hopefully there isn't any confusion.