The SL-C, like most mid-engined cars, suffers from imperfect rearward vision. At least until you do something about it.
The addition of rear-view cameras (as opposed to backup cameras, which only show the area directly behind and down from the rear of the car) and careful mirror design and placement can make a huge difference, removing blind spots, and making driving in traffic much more pleasant.
The two standard mirrors are the "door mount" and the "hippo ear" models. Either style is available as a no-cost option when the car is ordered. Both are made by the same company, and both are constructed of white resin, which is easy to finish.
The Hippo ear style, because of its mounting height, will generally provide a better rear view than the standard door mount style mirrors.
Both mirrors come with flat glass, with about the same area, and both are equipped with forward-facing LEDs under a clear fresnel-style lens so people in front of you can see an additional indicator that you are making a turn. You'll have to run wires to the mirrors if you want this function to actually work, of course.
To get the most from either of the stock mirrors, modifications can be done that improve overall functionality and appearance.
Many builders find that when they install the mirrors for the first time that the glass sticks out beyond the housing when adjusted for correct viewing. This is easily corrected in two ways.
For the door mounts, it's easy to grind the bottom of the mount to get exactly the correct angle so the mirror housing is mounted in such a way that the glass can be adjusted to look centered in the housing. To be sure you've done this correctly, make sure you are sitting in the seat you will use, installed and adjusted the way you will be when actually driving the car before you finish-install the mirrors.
The hippo ear mirrors normally can't tolerate a lot of grinding on the base for adjustment because of their design. To correct the problem of the glass sticking out past the edge of the housing on these, you need to build up the housing with epoxy or fiberglass and normal bodywork techniques. Adding about a half-inch to the outside of the driver mirror, and about 1.25 inches to the outside of the passenger mirror is usually needed. Check your mirror beforehand to get an accurate measurement for the mods needed for your own case. An easy way to extend the housing to accommodate the glass angle needed is to use stiff clear packing tape to build a sort of fence that extends the housing depth, and use thickened epoxy or FG resin to extend the housing. Peel off the tape when the resin hardens, and finish with normal bodywork techniques to get a perfect finish.
The key with these mirrors is not to wait until the car is mostly finished to install them. Be sure you get everything just how you want it before the car and its parts go to paint, or worse, until you drive the car for the first time.
Once you've extended the mirror housing so the glass can be moved to the optimum angle, vision can be further improved by replacing the factory-supplied flat glass with convex glass. The use of convex glass is typical in passenger-side mirrors, but the same thing can be used for both mirrors. It's easy to make the convex conversion- just buy replacement mirror glass at your local parts store (Advance, NAPA, etc.) and cut it to the same shape as the original glass. This writer used an inexpensive replacement passenger mirror glass for a Dodge minivan which cost about $18. You can take the original flat glass with you to the store and lay it over the replacements there to get a sense of not only size, but where you want to cut the new glass to get the maximum effect of the curved glass.
Cutting the glass is easy, if you are careful. Start with using good gloves as the edges you will be making are very sharp. Begin by placing the factory glass over the convex replacement mirror and tracing the outline with a Sharpie. Then use a glass cutter tool like this one to scribe the edges. Make scribes so you can break off pieces in an incremental way, using the cuts to make small, easy-to-break-off pieces that leave the original glass shape when done. Don't worry about nibs or an imperfect cut, as long as you leave a little extra material around the edges, as the next step is to carefully grind the edges to be smooth and consistent. Once you've ground the edges to the proper shape, checking often against the original glass, polish the edges with fine sandpaper. The new convex mirror is now ready to mount back into the housing just like the original.
In addition to the front-facing LEDs that can be wired to show a turn signal in the mirror, the factory mirrors can also be modified to show a turn signal to drivers behind you, and to the side. The easy way to do this is to embed an LED array under the glass, as it done in many OEM cars. When the turn signals are on, the LED array shines through the mirror glass; when off, the LEDs are invisible. Amazon and eBay have these in many styles and shapes. To install, just glue them to the back of the mirror glass with hot-glue. They can be wired in parallel with the front-facing ones.
There are many aftermarket mirrors available that can be fitted to the SL-C. Most of them can be mounted to the doors, and some of them can be fender mounted. Using the fenders, instead of the doors, allows a wide range of placement. Check out pictures of race cars to get a sense of how these have been mounted. If you elect to use aftermarket mirrors, pay attention to whether the glass is flat, the area of the glass (larger is normally better for improved vision at the expense of drag), and the stability of the mount. Few things are as annoying as a mirror that vibrates so much you can't use it.
Modifiying OEM mirrors
All of the factory mirrors have manual adjustment, are not heated, and are pretty much the size and shape they are. But using an OEM mirror from a junked car can be a way to get some of the technology features you may like, as well as generally larger glass area. Mounting them will almost always result in more work than initially expected, but if you are required to have electric mirrors (for example, the UK requires that the mirrors be able to be adjusted by the driver with the windows up, we understand). At least one SL-C builder has installed electric mirrors from a Mazda RX7. Here's that car- the mirrors look very good on it:
In addition to mirrors, a rear view camera can make a tremendous difference in rearward vision. We aren't talking about a backup camera, which typically shows the area just behind the rear of the car, and faces downward to help backing up, but instead a camera that is mounted up high, and is pointed straight back, in order to get a good view of everything behind your car, just like a normal center-mount mirror does in a car with a rear window.
Selecting a Camera
There are literally hundreds of different cameras that can be used as a rear view, from board cameras mounted on a circuit board, to re-purposed Go-Pro-style cameras, to dedicated bullet cameras, to specialized cameras designed for the purpose. There are too many to recommend one; the best approach is to try a couple (they can be pretty cheap) and see how they work with the rest of the system.
In general, you want a camera with about a 130 degree view, CCD sensor instead of CMOS, and the right shape to mount on your car. Cameras with external IR LEDs are generally not worth it, as the IR LEDs aren't powerful enough to illuminate much at night anyway, and will always get overcome with headlights, etc.
The ideal cameras for this purpose differ from the typical cameras sold for rear vision while parking. The parking style cameras have a wide angle, and their distortion at longer distances is not important when parking in close quarters. However, cameras intended for rear vision while driving at speed typically have a narrower angle of vision, are bloom-resistant (i.e., resist going white when confronted with a sudden light source like flashed high beams), may have a higher number of lines of resolution, and are typically powered constantly.
Mounting a Camera
Some cars have hidden the rear-view camera in a shark fin (many are available from eBay), some have made integrated housings that also incorporate rear brake lights, and some have just stuck a camera on with a small metal mount out in the airstream. All of the choices work, but have implications in terms of style, security and performance. Choose what makes sense for you.
In any case, the best place to mount them is up high, and in the center of the car. For the SL-C, that normally means a mount at the back of the roof scoop, about 6-12" from the back edge. Be sure that if you are running a rear wing that the view is not obstructed so much by the wing that you can't see- careful mounting is key here. Here is a small gallery of rear-view cams on SL-Cs:
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Mounting a camera is only half (or less) of the task. You have to have a way to see the video output from the camera which driving the car. That means some kind of display. Like the cameras, there is a wide range of choices. In general, you want to have a display that:
1. Fits in your car where you want it
2. Has resolution that is consistent with your camera output
3. Can be seen in all lighting conditions, especially bright sunlight
4. Can be adjusted (preferably automatically) for ambient light conditions (a very bright screen will destroy your night vision)
5. Does not block forward vision
For most people, that means mounting the display in the center stack or in the roof panel. Please resist the temptation to tack it on the dash with a flex mount- that will block your forward vision in addition to the obvious visual clutter it introduces.
A roof panel mount is usually better, as the eye has been trained to look up for a mirror, as in a "normal" car. It is also better for shading in bright sunlight. A display mounted in the roof panel can also be motorized so it can flip up completely out of the way when that is desirable.
There are hundreds of possible LCD screens available, including many that are designed to be clip-ons for standard mirrors. There are also dedicated monitors that can show multiple camera inputs at once on the same screen.
Tablets are often thought of as an alternative to dedicated display screens, as they are typically thin, easier to mount, have lots of internal battery storage, and can run other applications besides the camera function. However, there are relatively few of these working in practice, as the complexity required to make them work, including a charging approach, has generally been too much except for the dedicated enthusiast with a lot of time and expertise.
Wired vs. Wireless
Normally, the display is connected directly to the camera with an RCA cable. This is usually the easiest and best way to connect a camera to a display. However, there are wireless cameras that use wifi to transmit the video signal. These have the advantage of being able to send video to devices like tablets that don't natively have RCA inputs, but at the cost of about a second of latency (in other words, what you are seeing on the screen happened a second or more ago). For backup cams, this is probably acceptable, but less so for real-time rear-view applications where the cars around you are moving at high speeds.