Is it time for automakers to get the fat out?

andre1969

Sometimes I do wonder what would happen if the auto makers had applied all the fuel economy improvements to cars, but without all the stuff that added weight. For example, instead of taking the Accord to where it is now, what if they just kept the 1990-93 style? But gave it a modern 5-speed automatic and a 2.2 liter version of the engine that it has today? And kept the smaller tires and wheels from the 1990 era?

My guess is that you'd end up with better economy than the current Accord, but still not as good as the Civic, which is still lighter and has a smaller engine. It would probably perform better than either of the two, though.

I guess one reason that I question how much weight really comes into play stems from when I took a trip down to Florida 3 years ago. We took my 2000 Intrepid, and had three people on board, the trunk stuffed to the gills, and some luggage spilling into the back seat. I imagine those two extra passengers, plus all the luggage, easily added 500-600 lb to that car. As for fuel economy? I averaged 27-28 mpg on that trip. Mostly highway, but stuck in some traffic jams,and running 70-80 mph as much as possible, a/c running the whole time.

However, 27-28 mpg is about what I'd get with that car if it was just me on board, a/c cranked up, running 70-80 mph. So in this case, that extra 500-600 lb had a negligible effect on economy. Now I'm sure if I did more local, stop and go driving, it would've been felt.

nippononly

Sure, highway mileage is all about momentum. Once you have the thing cruising at 70, it only takes a very small percentage of the engine's power to keep it at that speed. OTOH, lugging all that weight away from stops drags the fuel economy down.

texases

Are vehicles too heavy? Yes. Surprisingly, my favorite example of weight control is that ugly American, the Corvette. They weigh no more today than they did 20 years ago! Contrast that to any other car, domestic or imported. The major culprits in weight gain? As mentioned, it's a combination of size, power, handling, comfort, and safety. How many car reviews have you read that said "the new Whatever is 50/80/120% stiffer than the old model"? And how many ads trumpet 5-star crash performance? So don't kid yourself, to get lighter cars will require us to sacrifice some combination of size, power, handling, safety, comfort, and money. Car designers aren't stupid, they don't have blocks of iron hanging off that can just be deleted.

lemmer

I am a big Porsche fan, but it is embarrasing to me how much better Vettes have done with weight than 911s over the past 30 years. Off the top of my head, I can't think of another car that has lost weight over that time period. Similar engine, similar size, a lot more space inside on the new one, and all the safety stuff has been added. How did they do it?

nippononly

The real trick for automakers will be getting weight under control in models that DON'T cost $50K, and seat more than two.

It is a shame that no-one ever touts the advantages of lower weight in marketing. If they did, we might have people clamoring for lighter cars, giving automakers financial incentive to do something about the pork.

texases

"How did they do it? "

Well, you could say that they had lots of room to improve, what with the earlier Vette's heavy frame, etc. They really went after improving the chassis through better design, rather than more metal. Don't they use some kind of balsa composite in the floor for stiffness? And aren't the springs now fiberglass?

andre1969

I'd imagine they've also seen some weight savings in the engine block, itself. Now I don't know how advanced the Corvette's engine was 20 years ago, but the Chevy smallblock was always a pretty chunky little engine. Low reciprocating mass and small size yes, but in overall weight it was a bit of a porker.

Still, I'm sure just about everybody has saved weight in their engines compared to 20 years ago yet the cars themselves are often heavier, so evidently the Corvette has been toning down the excess in other areas, as well.

texases

"I'd imagine they've also seen some weight savings in the engine block, itself."

I think you're right, what with the current aluminum block, heads, etc. Another weight-saver (well, weight gain avoider) is the continued use of the OHV design. Gotta be saving a lot of weight compared to having 4 OHCs, had they gone that route.

ronsmith38

Maybe we should look at "weight per passenger". A 5000 lb vehicle that can carry 8 would have a 625 lb per passenger number. A 3000 lb vehicle that can only carry 4 would have a 750 lb per passenger number.

nippononly

Nah. The problem with that approach is that whether it is a vehicle designed for 4 or 8, it will most often be carrying 1, or 2 at the most. Americans overbuy when it comes to their vehicles.

And either way, as Lovins points out, the percentage of a car's curb weight that it can carry as passengers and cargo is much too low.

lemmer

In one of my cars, I like some reserve capacity just for convenience. I have a family of four, but sometimes I throw in a couple of grandparents or somebody else's kids. On the other hand, the car I drive barely has room for the four of us. I think We all overbuy because the incremental cost of doing so has historically been so low.

nippononly

Well yeah, and even now it isn't really that high. But my point was not that people shouldn't have a larger vehicle if they want one, but that lb/passenger ratios were not very telling, and even counter-productive.

I do feel strongly that all vehicles should be much lighter, even (especially?) the really big ones that can carry 7-8 passengers.

lemmer

My Pilot seems like a beast at 4400 lbs until I see a Suburban at over 5700. Unless you are towing a mobile home, why bother?

kernick

Why couldn't vehicles be manufactured to be modular such that you would buy something like a CRX as the base component or the front of a Chevy Avalanche, and then if you need the room you buy a modular add-on section?

That way you could have your Smart-car like vehicle, and have the option of the versatility. I could see the price of the Base section at $15K - $20K, with the optional add-on section being another $7500?

The base section would have 4-wheels, an engine and the controls. The base section would have a rear panel that drops down, and a mating-surface for the add-on section. The add-on section could be a pick-up bed or a rear-seat/trunk section. It would have 2 wheels for balance; so the vehicle has 6-wheels total, with only the base-section driven (either 2 or 4 WD there). You could also install electric motors and batteries in the wheel-wells of the add-on section if further drive was needed.

ronsmith38

A coworker of mine did just that 25 years ago. He had a pickup and added a cap, then bolted in seats (and belts) from a junk yard as his family grew!

andre1969

I think the biggest problem is that just the modularity is going to add weight. Instead of one big component, you have two smaller components that both need to be able to stand on their own without falling apart. Then there's the added weight of whatever keeps the two components joined together.

Another problem is picking the correct-sized engine. Pick an engine that's adequate for just the main component, then once you hook up the secondary part it's going to be too much weight for it. In contrast, pick an engine that can move the whole contraption, and when you're just using the main component, you have an oversized engine that's wasting fuel.

nortsr1

I also beieve there would be a safety factor involved as far as passing our tough safety standards.

lemmer

Does anybody remember the Nissan Pulsar with the modular back? That went over like a lead balloon.

michaellno

Funny you should mention that! There is a picture of one in the "Mystery Car Pictures" discussion - with the SportBack attached.

kernick

Instead of one big component, you have two smaller components that both need to be able to stand on their own without falling apart.

Not really; think of the rear add-on section as a trailer which doesn't move on its own. The drive section and the add-on could interlock similar to a trailer on a trailer hitch, but with 2 balls so it would stay linear.

Pick an engine that's adequate for just the main component, then once you hook up the secondary part it's going to be too much weight for it.

Trains and those double tractor-trailers can be designed to carry vary loads, so this isn't rocket science. So you would oversize the engine a little for the drive section making it sporty, so it is adequate with the add-on. Or as I said you could have electric motor drive recharging from the engine in the rear wheels.

andre1969

Trains and those double tractor-trailers can be designed to carry vary loads, so this isn't rocket science. So you would oversize the engine a little for the drive section making it sporty, so it is adequate with the add-on. Or as I said you could have electric motor drive recharging from the engine in the rear wheels.

They also make truck tractors and railroad locomotives with varying amounts of power, mated to the task at hand. You're not going to use a rig designed to haul, say, 10 tons, to move a 40 ton load. And with trains, when the load gets too long, they have the option of adding another locomotive.