I just received the shipment from SuperBrightLEDs, but it will be Monday before the parts from Mouser arrive. What follows is my report so far.
INTERIOR "DOME" LIGHT: (turns on when you open the doors or manually switch it to On)
This light has a holder with a twist lock. Standard wedge base bulbs plug straight into the holder and then the holder is twisted into the fixture. The fixture itself can be disassembled, but that's only for the very brave and adept.
So far, my recommendation is the $4.95 WLED-WHP. Its 120° beam covers just as much area as the original incandescent. I would have preferred natural white, but the only available white is "cool white." It puts out a healthy 15 candles (15000 mcd) of brightness, which is at least as bright as the original. I noticed that the original 5 W incandescent is too hot to touch after it's been on long enough for you to remove the socket, but this replacement is only 0.3 W - quite a bit less wasted energy (94% less waste!). Note that both times I installed it, I got the polarity backwards, and it did not light up. If that happens to you, then quickly remove the base, rotate 180° and reinstall. I cannot remember whether this LED is protected against reverse polarity power, but it did not burn out after two brief instances of reverse voltage. Thankfully, you don't even have to unplug and replug the wedge base bulb itself, because the twist lock holder fits two ways.
I tried the $3.94 WLED-NW5, which is supposed to have a 220° beam, but it just barely did not fit into the fixture using the normal procedure for replacing the bulb. It's theoretically possible to fit it in there by disassembling the fixture further (see below) and plugging in the bulb after the holder has been twisted in, but I did not bother since the brightness is only 2 candles and I don't think that the wider beam would be of any use.
I disassembled the fixture with the hopes of fitting in the $11.95 WLEDB-CWHP4-DAC, but ran into a couple of problems. First of all, the killer is that the ring into which the four LEDs are mounted is literally too big in diameter to fit behind the bezel. A second problem is that I would not recommend disassembling the fixture for most people. It takes a rather delicate hand to take this thing apart without breaking it, and the real challenge is getting the it back together. You can see why I did not go back and try to fit the 2-cd bulb.
TRUNK LIGHT
The standard festoon bulb that comes stock is 37 mm, so the best replacements will be 37 mm, too.
Here I recommend the $14.95 3710-CWHP6. It's the brightest they offer, at 66 lumens, and the over-sized package actually fits just fine. Here, you drop from 5 W to 1.632 W, an energy savings of 67%. Again, the original bulb gets very hot and that really seems like a waste to me. Some of you who actually like the warm color of incandescent bulbs might prefer the 3710-WWHP6. Unfortunately, you still have the original problem that if one piece of luggage covers the tiny light you can't see the rest of the trunk. For me, the convenience of replacement far outweighed the potential advantage of installing something completely different. Besides, every trunk has a single light that can easily be obscured.
I also tried the $7.95 3710-CWHP3 and it seemed fine. It's half as bright as the HP6, but still plenty bright compared to the original. Power is about 0.6 W, or 87% less than incandescent. Also available in warm white as 3710-WWHP3.
I tried a couple of the 3610-xW4 bulbs, but here you have a slight problem. After removing a 37 mm bulb from the socket, these 36 mm bulbs fit loosely and flicker on and off. They're also rather dim for the trunk at only 5 lumens (4 lumens for warm white).
LICENSE PLATE ILLUMINATION
There are two bulbs and holders here, with the same 37 mm festoon bulb.
All of the same LED bulbs fit, but I notice that they're all much brighter than the OEM incandescent bulbs. Since I have an ongoing problem with the license plate lights causing glare in my backup camera lens, I chose the dimmest LEDs available. I wouldn't call it lens flare - what actually happens is that the light coming in at a 90° angle from above just makes the cheap plastic lens look fogged. With all the fogging in the headlights, I assumed for a while that the backup camera lens was fogged on the inside, too, but it turned out to be the license plate lights.
It's possible to fit the 3610-xW4 festoon bulbs into the license plate light holders by squeezing the metal springs slightly closed before fitting the new bulbs. You only need to make them 1 mm smaller, which is not too difficult. So far, I don't think that my license plate lights are flickering due to the undersized bulbs, but that may not last. I hesitate to recommend this option since they're technically not to spec. Anyway, once installed, but before screwing on the plastic lens covers, I rotated the directional LED while looking through my rear window at the Alpine in backup camera mode, until the lens looked completely clear. This reduced the brightness quite a bit, but considering that the LEDs are already ridiculously brighter than the incandescent bulbs I think it ended up about the same. On the side opposite the backup camera, I just aimed the LED straight out for full brightness.
These bulbs are only $2.84, so I guess I'm not too picky that they aren't perfect matches.