I'm of three minds about the situation... Here are three perspectives:

First: The W123 is not a perfect car. MB engineers aren't gods, and MB is indeed a company trying to make money. Each and every part is not the best possible part for the job, it is the closest fit they could find from things they've already built and items already on the production line. They did a great job of it all, but not a perfect job (anyone with cruise or ACC problems knows full well how imperfect it is). Based on this mindset, I feel comfortable changing the car's stock parts to newer systems that work better. Did MB not put an intercooler onto the car because it is perfect without it? No, they did it because it didn't meet their cost and performance goals in an automotive world over 20 years ago. If today's cheaper/better intercoolers are an option for better engine operation, why not do it?

On the other hand: There is value in a 'stock' car. People who, 50 years ago, treated 'common' cars like they were worthless in their stock form are now kicking themselves when their highly modified antique car is not worth as much as a stock antique car. Why take a perfectly good car, that will probably make it to 'antique' age if well cared for, and mess it up for the future? Take a deep breath, love the car for what it is, and keep it that way. If you want whizbang, buy a newer car.

Somewhere in the middle: No need to shy away from improved parts for better safety and performance, but if something isn't broken, don't fix it. Why put on crazy wheels and ground effects if it doesn't need them? However, if the 'stock' shocks or exhaust system aren't up to the standards of today's options, go ahead and upgrade, to make the car safer and better, without destroying its classic appeal.

Now personally, my car is in a transition state... It has its original engine and transmission, original paint, and mostly original glass. However, the wheels were replaced with CLK wheels (which look great, but are far from stock). The windows have been tinted, and the stereo and speakers have been changed. Also, the paint job is far from perfect, and will soon need a repaint. When the time comes to repaint, I'll make sure the job gets done right, and I'll repaint in the original color (I like silver anyway), but that job will DROP the value in some peoples eyes, and RAISE the value in others. Its a confusing balance. This car I'm not committed to keeping 'stock' because its not stock right now (and I don't have the money or inclination to do a 'stock restoration'). However, I probably will not do any cosmetic or wild performance mods, since the car is great the way it is. However, as parts break I won't shy away from using more updated components as replacements.

If my car was like my grandmother's dead-stock, pristine condition '78 300D, I would try to keep it that way. It is a car that is destined to become an antique, and I wouldn't want to change that.

However, say my 'mostly stock' car was to be in some sort of wreck, destroying any possibility of a restoration but without destroying the usability of the car, I'd consider some serious automotive artwork, and let myself go a little more crazy with performance mods. I'm talking a lift kit, faux body armor, flame throwers, propane injection, and a flame job. Nothing I'd dare inflict upon a perfectly good 300TD, but something I'd consider if the possibility of restoration was no longer an option due to some major damage.

Anyway, don't be too unhappy when you see 'pimped out' older cars, since they may be cars that weren't in a restorable condition anyway. If it is in a wreck and has a frame straightening done and some welded on structural repairs, it isn't going to be a 'collectible' anymore, and is free to be played around with. However, if someone took my grandma's 300D, got a cheap re-spray to red, threw on a cheap HID kit and rolled the fenders to fit 20" wheels, I'd be pretty unhappy.

So, I suppose my answer to the original question is: "Depends."

Peace,
Sam

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"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)