Why do dome lights burn out after a couple years, but the dash lights last for the lifetime of the car? Why wouldn’t they just use the same light bulbs in the dome light and save us the trouble of replacing it?
if they used the same bulb in the dome as the dash you would see a glow on the ceiling. if you put a map 2 inches away from it you might be able to read it.
greater illumination over a larger area is had by larger filaments and higher currents, both contribute to a shorter bulb life. a ‘grain of wheat’ bulb in a model train can last for half a century or longer.
You are obviously not familar with cars from the 60’s and older. I have owned quite a few of them over the years and I can’t think of one that didn’t have a dash llight go out at least once. I had a 64 Mercury Comet that would burn out a couple a month, I don’t think I ever changed the dome light bulb. My current vehicle uses LED’s for both the dash and dome lights, hopefully I will never have to change any of them.
I briefly owned a 1964 mustang, but my grandfather buried it in his back yard before I got my license, so never got a chance to drive it. 
A couple years later, I owned a (bitchen’) 1979 Camaro with some sort of electrical/wiring issue such that if I used the cigarette lighter, then dash lights fuse would blow.
I was going to post a follow-up question about LEDs in cars. If you don’t mind, what sort of car do you have? I just bought a new Accord, but alas, it has plain old hot bulbs.
For pretty much the same reason they don’t use the same bulbs in the headlights. The bulb is selected for its light delivery, not its longevity.
No American vehicle made between 1974 and the mid-80’s can actually qualify for ‘Bitchen’ (sic) status, as you put it. Maybe – just maybe – the late 70’s 6.6 Trans Am with the ‘‘screamin’ chicken’ on the hood (and I am saying 'maybe’).
From 1974 until the Buick Regal Grand National showed up in full boost form in the Mid 80’s, ain’t nothin’ that was bitchin’.
Operating a bulb at reduced voltage dramtically increases it’s longevity. Instrument lights rarely operate at full voltage. Efficiency is poor at reduced voltage, and the light has a reddish cast. This is no problem in an instrument cluster that only uses a few watts, and the reddish color can be argued to preserve night vision.
A 400 CI engine that pumps out 200 HP is not bitchen’ no matter HOW much torque it delivers. If you were to aim the fuel pump output at the rims and run it like a water wheel you’d get more mileage AND better acceleration. It was and remains a white trash car suitable only as a trailer park yard ornament.
You obviously have never removed the entire dash assembly from a ‘91 Thunderbird just to replace the flippin’ bulb.
The Dead Milkmen may disagree with you on that subject, since their single “Bitchin’ Camaro” was on an album released in 1985. Since that song is full of awesome, I have to concur with their opinion - though you may have to actually be playing the song on the car stereo for the real bitchin’-ness to come out.
I might also wager that less exposure to the elements, directly, would help the dash lights last longer. The thought of a headlight flicking on for a very cold winter night, versus a tiny light inside the car, makes me think that the larger bulb might be under more stresses due to temperature changes, rain, etc.
Ahem.
ETA: Ferrett Herder is wicked smaht