For the environmentalists and engineers: Can we design a modular car?

Great Debates
1

As I was driving yesterday, I considered my current and future vehicle needs, and how I could possibly use vehicles that use the least amount of gas. My wife and I have a 10-year-old Geo Prizm, which does OK on gas, and a new Honda Element, which does OK on gas (for a small SUV) and has the cargo space we often need–often, but not always; sometimes, we just need a second car to move one driver, and don’t need such a big vehicle. Ideally, I would like to have a Honda Insight (70 mpg) for routine human travel (i.e., most days that my wife commutes to work, and most business trips that I make), and use the Element only when we need the cargo hauling space.

But, of course, I don’t have the cash to dump into that many vehicles. And the simple fact of the matter is, if I have to choose between a vehicle that can meet all of my various transportation needs (2 people, extra passengers, cargo hauling) and one that only meets one (2 people), I’ll pick the former.

But I still resent having to haul all of the Element’s bulk around on days that I don’t need to fill it with cargo. Which got me to thinking: Why can’t we have a modular car? That is, a fuel-efficient (possibly hybrid) coupe onto which you could snap a cargo compartment (with wheels) when needed? Sure, you could just attach a trailer, but they’re tougher to handle on the road than a non-jointed body. The rear pod could be either more seats (for soccer moms), or enclosed cargo space (what we usually need), or even an open pickup bed (for hauling dirt, construction materials, etc.).

Now, I know that there are mountains of engineering problems to tackle here: making a snap-on mechanism that will create a strong, safe (and weathertight) attachment; making a mechanism that can reasonably be attached or detached with no more than 15 minutes of effort; making sure that the engine of the small coupe can handle hauling that big thing behind it, that its brakes can stop it, and that the extra oomph you’ll need on those occasions when the pod’s attached won’t require such a big, gas-guzzling engine as to make the whole thing a wash.

So how about it? Are these problems mere challenges, or impossible obstacles? And would having more of these things on the road reduce overall gas consumption?

2

Mere challenges.

As to your questions there are better and easier things we can do to reduce gas consumption than making modular cars. The biggest and easiest is just to use smaller more efficient engines on cars.

3

http://www.gm.com/company/gmability/adv_tech/600_tt/650_future/autonomy_050103.html
Yes, there have been experiments that way, towards a modular car.
Some people think it is the wave of the reduced-number-of-automobiles future. Most don’t.

4

I think you’d find that a ‘modular’ car would gain you far less than you’d think. The drivetrain would still have to handle the heaviest configuration, and that’s where most of the weight is anyway. There’s really not that much difference in weight between a ‘compact’ car and a small SUV. Most compact cars approach 3000 lbs in weight - maybe 2600, 2800 lbs. Many of them are over 3000 lbs. A compact SUV body only adds a couple of hundred pounds to this weight, and even a large behemoth is only a thousand to 1500 pounds heavier, and a good part of that goes to the beefed-up drivetrain required to haul that weight around.

Plus, a modular car is going to be heavier with all the modules attached than a unibody would be, because of all the extra stiffening required for the ‘modules’ that aren’t part of the integral structure of the vehicle. And, the ‘base’ car will be heavier than an equivalent compact car, because it will still have to haul around the extra weight of the stronger structure required to manage the modules.

5

You only need the wagon once in a while?

Option 1: A (very) small trailer for the Prizm and Insight
Option 2: Rent a van when you need one.

6

This is what I was going to mention. Scientific American’s TV show (the one hosted by Alan Alda) featured this about a year ago on their vehicles-of-the-future show. Basically all of the mobility engineering (wheels, motor, fuel cell, etc.) is contained in what looks like a big skateboard; the passenger compartment on top is interchangeable. Definitely a number of years away from market, and there are some challenges that may prove difficult to solve (per Sam, if you have only one skateboard, how do you achieve the varying power requirements of one passenger vs. carload of band equipment vs. towing a trailer), but it was awfully clever and flexible.