Underride, Override, Anyride - Car Height's Still a Problem

About a dozen years ago, someone in the auto industry made the startling observation that not all cars are created equal. It may have been the National Safety Council or the Insurance Institute for Highway Safety or Jack's Auto shop, no one really remembers, but the argument boiled down to this: car ride height (height) differences were contributing to the rising cost of car crackups.

This germ of an idea became pretty well planted into the national consciousness after a particularly gruesome series of accidents involving low, sleek models that were just tall enough to have their roofs ripped off by big tractor rigs and some of the taller Sport Utilities. The government, of course, its wisdom, reacted and said that it was up to the trucking industry to solve the problem as it was up to auto industry to solve the problem. It would suggest a federal rule to cover it - there were already ride height rules in place that were seldom enforced because the climate in Washington from about 1980s on was definitely pro-industry and anti-regulation.

So, the truck industry actually did do something about it. They took a couple of rather large I-beam assemblies and welded them to the rear end of trailer rig and then rather than just having two legs sticking down, they welded a large I-beam assembly across the bottom of the vertical legs so that it was U-shaped. It did stop the car-intrusion problem and those ghastly accidents.

The car industry responded with its usual yawn and went back to business as usual. They made some attempt at dropping the height of the rear bumpers of pickups and Sports Utilities - actually the same vehicles with difference bodies -- and that seemed to work for a while because designers actually - while still yawning, mind you - took the words to heart and they designed front ends that actually mated pretty closely with the rear ends of pickups and Sport Utes (SUVs). So, the problem was solved, right?

For a few years, the answer to that question was an unequivocal yes. It didn't stop crash costs from being huge when a car rammed the rear end of a pickup or SUV - the laws of physics don't change and one item hitting another items at a certain speed needs to get rid of the inertia (energy) somewhere, and that meant ripped up front ends, engines that dragged on the street and body panels that ended up looking like a pretzel-maker's worst nightmare (the Nightmare on Pretzel Street??).

All kidding aside, someone in the research and design departments of the auto manufacturers was actually watching all this and did some homework. They developed a whole series of safety fixes that worked to keep people healthier than they would be if they were surrounded by the traditional ladder-frame, stiff-bodied vehicle.

For instance, the auto industry studied the force of accidents and determined that as cars grew smaller and mismatches occurred, it would be far better if engines were breakaway affairs - look at an engine mount and how an engine compartment is designed for confirmation - that actually moved down and away from the car during a front-end accident. In other words, the engine slid under the car as much as possible to eliminate passenger compartment intrusion.

Then there was the idea - pioneered by Europe - called microsiping. Most car panels look like they are nice and solid affairs, and they are - in a way - on the outside. Underneath, on the inner panel - if you were to look at it with an 8 or 10-power magnifier, you would see a series of striations at very regular intervals - about an-eight-of-an-inch. This is called microsiping and the idea is the make the inner liner think it is longer than it is. Think of an accordion bellows or fireplace bellows. They are relatively thin devices, yet they get huge amount of air through them. The reason is the bellows and siping. Each plate of the bellows is V-shaped and when you pull them apart you draw in a huge amount of air that is squeezed out (venturi effect) a small nozzle. The accordion works the same way.

Well, safety designers, seeing this idea (maybe one was an accordionist in his hobby time, who knows??) tried various siping schemes with pieces of metal and determined the optimum crushability or deformability of various body panels and this was put into the mix sometime in the last dozen years or so and cars gained more safety, especially as airbags became more sophisticated and covered more or the vehicle.

An old problem was starting to rear its head in the late 1990s. The need to make vehicles more efficient as they flowed through the wind to save on gasoline, as well as the need to use materials substitution (ABS plastics, more fiberglass and other more exotic body panel materials - lighter aluminums and steels) meant that the jellybean shape, popularized I the 1980s and which was preceded by the wedge shape - became even more pronounced.

In the designs of the late 1990s and now 2000s the jellybean shape of say the Honda Civic or of the Toyota Prius or something as mundane as the Hyundai Accent brought an old nemesis back into the automotive lexicon, underride.

Looking at the Honda Civic designs of the 1990s showed they started out with narrowed front ends that swept through the rounded bodies and then on out through the rear deck, you could see that change had to happen because the danger of underride was quite apparent.

Starting about 2000 - with the restyle of Honda's Civic into a more traditional sedan - the problem of underride was lessened. The same was true of the other manufacturers. One manufacturer that led the way, believe it or not, was Ford whose brand-new Focus (at the time) was about to use swooping lines and effective bumpers for protection to produce a nice little vehicle that regularly achieved 25 mpg around town and handled like a charm (the engine was a sweetheart four). It's impossible to know if others took their cues from the Focus or what have you, but there you have it. A very nicely rounded conservative shape that still cheated the wind.

This shape was to prove popular with just about every many manufacturers during the first half of the decade and there was nothing wrong with - apparently because dealers really never heard complaints. But, the year was coming up on 2006 and it was time for the Civic restyle and the jellybean raised its specter again. This time, though, the engine compartment slanted low so that now only was the shape rounded, but it also was somewhat wedged. This meant for clean airflow and top economy.

It also meant that if there was an accident with a more standard vehicle, the Civic lost the battle because it underrode. The ride height difference raised its head again and any time there was an incident, the Civic's front end rode down and under the vehicle it was impacting. Civic.

Other vehicles that used lower rear ends and more hatchback style rear ends suffered from underrides overrated twin, override. In this instance, the vehicle doing the impacting tended to ride up on the trunk area and come down. So, at once, problems that had been dialed out of the automotive lexicon for some years were back. Underride and override, both of which, the Institute for Highway Safety point out can be expensive alternatives, unless you take Ford's hint and still a wind-cheating vehicle that still believes that bumpers are for protection and that a higher rear end doesn't mean that you lose mileage.