so i was reading the thread on the guy that wanted to put a 240d engine in an 300sd for better mileage, and it got me to thinking. what if someone where to take a 240d, remove the fenders, hood, truck lid, and the rear quarter panels and make a set of each of these from carbon fiber or fiberglass? i know this is far fetched and the amount of money required to do so would be economically unfeasable but, if this where to be done how much of an increase do you think there would be in fuel mileage/performance?

if you are going for performance i would just look at a different car. i have the 300d for its driving and solid car. i would not want to take all the armor off the car and make it more dangerous than a geo metro.

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Grey '91 350SDL 214k Dad's car
Beige '81 240D 4 Speed 254k SOLD
Blue '82 300D 225k SOLD
White '95 E300D 46k SOLD
Blue '87 190D 2.5 Turbo 315k SOLD
Brown '80 240D 4 Speed 716k SOLD
Beige '80 300D N/A 119k SOLD
Blue '85 300D Model 186k T-Boned

Though it would decrease weight somewhat. the sheet metal that could be easily replaced (fenders, trunk lid, hood), doesn't add up to too much weight and I think would be expensive to fabricate in fiberglass. As far as the Panzer(tank)-like safety concerns, I find it hard to believe that the sheet metal in these assemblies confers the majority of the protection offered by the cars. The frame and steel-safety cage probably do this. Fiberglass, done right, can be stronger than steel sheet and give some bouce, so it might be even more protective than what is there.

Now as regards things you could remove to lighten the package, removing the US bumpers is pretty easy and might do something for you. They are probably 50-70# combined, and the US ones certainly do not help the aeordynamic efficiency of the vehicle. Interestingly, they also don't serve much of a safety function, mainly having an effect at <10 mph and even there primarily serving to minimize damage to the vehicle in a low speed collision. they are there more for your insurance company than for you. So running without them or with Euro replacements (which look neat) might be one way to drop a little weight and improve aeordynamic efficiency.

And yes I'm the who wanted to put a 240d engine in a 300sd chassis.

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Der Panzermann und Fraulein Fahrvergnuegen

1991 420SEL 201K "The Big Blue One"
1985 300DT 205K chassis/285K engine nee California emissions "Goldbug"
1983 300TDT 255K "The Womble"
1983 300 DT 214K "Sea Sprite"-Rear-ended a truck
1983 300SD 285K "The Donor" Gave his life so that others can live
1980 500SL Euro 105K "Der Panzer"

Does anyone remember the Hot Rod article on free horsepower? They took a 472 Caddilac 2 door and gradually cut off parts all the while recording quarter mile times. Amazing what a little weight loss will do. Cut that sum***** down to nothing and see what kind of fuel economy you get.

Weight reduction to improve milage is not a great factor. More than one manufacturer has tried it and the majority have failed. Design of engines and gearing etc can and has beem the most responsible element in getting better milage. Even mercedes tried incorporation of a lot of aluminum panels in their cars at one time with virtually no difference. But they do accelerate better. If you dropped a thousand pounds off a 240d I would expect it to feel a lot peppier for instance. As for milage gain some of course but probably not nearly as much as one would expect. Some mercedes rust buckets may have lost almost that much in oxidation and I have not heard of any milage increase. Some large tractor trailors get about fifteen mpg loaded it is claimed. The trippling of fuel milage has not evolved through less weight. Rather instead it is because of engine design and management systems primarily.

Fiberglass can get pretty heavy...especially if you want it to be fairly strong.

What would definitely be lighter would be plastic....You might be able to talk a rotomolder to make some smaller pieces. The larger and more complex the mold, the more money it costs. The part itself will be relatively inexpensive...maybe $70 for a trunklid out of HDPE (although HDPE gets a little soft in the summer sun, plus you would have to match the plastic to the paint)
A plastic injected mold would be way too expensive.

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

But there's probably a lot of rust still hanging on the car. Note that rust is heavier than the original steel.

Matt,of course you are right. Before safety requirements were heavily enforced the 114 type would exibit almost total loss of any sheet metal below the belt line and still be on the road. This was in our bad rustbelt area. There is a salt mine extending miles out under the ocean about twenty miles away. Any employees car from there you do not want to see or buy. On a car like a pontiac grand am the disimular metal in the floor pan and lower panels results in a gap of about an inch where they join. This takes 6-7 years and to try to remove a fastening from one is generally imposible as they just round off.