Learning to drive upside down…

The “Led Sled” Copyright © 2005 Gawain Reifsnyder

I decided to start my midlife crisis early. I got a sports car. You might argue that my midlife crises actually began when I was 17 and got my first streetbike, but I digress. Since 2005 I’ve been the proud owner of a 2005 Honda S2000. Except for the limited cargo and passenger capacity (which I only miss occasionally) it’s pretty close to the perfect car for me. It’s well made, light, precise, fits me like a glove, makes wonderful sounds and is very quick indeed when I decide to turn up the wick. The chassis is and suspension are nearly perfectly balanced for the engine and the rear wheel drive make it just “tail happy” enough to be fun. There’s nothing like running through the gears on a country road, hearing the engine soar up to 8,000 RPM, then heel-and-toe downshifting into slower turns.

Aaah, the challenges of driving… Sadly, in the real world it’s not always possible, practical or safe to drive like this. So what’s a driver who enjoys a challenge to do?

Hypermile!

There’s quite a few explanations of of hypermiling around the web these days, but the basic idea is do drive in a way that maximizes the gas mileage potential of your vehicle. Some people take the concept to extremes and get huge gains in gas mileage, but some of the more radical techniques (like shutting off your engine at stoplights or when coasting) can increase wear-and-tear on your car and negate any of the money saving benefits. So, I’ve adopted some techniques that work for me. I get to keep my air conditioning, I almost never turn off my engine when waiting in line or idling, and I don’t drive so slowly as to make other drivers mad. Even so, I’ve managed to increase my gas mileage by about 23% to around 31mpg, and I’m expecting more gains as my skills improve.

For me, the basic mindset can be summed up as: “Coasting is good. Unnecessary throttle, braking, or engine braking are bad.” I’m always thinking about ways to maximize the time I spend coasting off-throttle and minimize the amount of braking I do. Gradual acceleration while using the highest gear practical is important. It’s another type of driving challenge, and one that I’ve found to be quite satisfying, especially when passing yet another gas station with a smug grin on my face.

Sports Hypermiling

I’ve found that hypermiling a sports car can be a little bit different than a normal car. A sports car’s design has some inherent advantages and disadvantages when it comes to gas mileage, and knowing how to address these differences is important to getting the most out of your sports car hypermiling experience.

Advantages

6-speed manual transmission

Gives you the flexibility to select the perfect gear for the speed you’re traveling. On the S2000, this often means shifting out of 1st almost immediately, and short-shifting up to the higher gears. The quicker you shift, the less time the car spends decelerating between shifts. On a flat road when traffic allows me to accelerate slowly, I’ll get to 6th gear at around 33mph. Applying anything but a tiny amount of throttle at this low RPM isn’t good for the engine so I only do this when can take my time getting up to speed.

Sticky Tires

You’d think this would appear in the Disadvantages category (and it does) but the supremely sticky rubber does provide one important advantage: higher cornering speeds. Slowing down less for turns means less fuel-burning acceleration exiting the corner. Of course, safety comes first so don’t blame me if you wad your car while trying to save a thimbleful of gas.

Coefficient of drag

Sports cars cut through the air with a relatively small amount of drag. When coasting, chances are you can go a tiny bit farther than your neighbor’s rolling tool shed, and that slippery profile means your car requires less power to maintain a steady speed.

Power-to-weight ratio

Sports cars usually have a higher power-to-weight ratio than a standard grocery-getter. This means that when hypermiling, the engine can get more done with less work. That free-flowing intake and exhaust system that give you more power (and suck up tons of gas) when you’re giving it the beans also mean that at low throttle settings you’re not using much more gas than lower powered cars.

Disadvantages

Engine Braking

Remember coasting being good? The S2000′s high compression ratio means tons of engine braking. Let off the throttle and the car quickly decelerates. This effect is obvious when you abruptly lift off the throttle, but even when using the cruise control the car may be subtly engine braking downhill when it could be accelerating while coasting and saving you gas. Combating this effect is tricky and requires that you pay attention to the terrain. When safe, try and gauge whether your car would accelerate downhill if you pushed in the clutch or coasted in neutral. This takes time and a bit of “feel,” but with practice you’ll get the hang of it. If the answer is yes, then either push in the clutch and coast, (best on longer hills) or feather the throttle until you’re just barely accelerating down the hill.

Sticky Tires

Here it is again. Fat, gooey rubber is great for hooning around on twisty roads, but it also is a source of considerable rolling resistance. There’s no easy way around this short of putting wheels and tires from a Prius on your car (ewwww) but you can get the most out of what you’ve got by keeping them properly inflated, erring toward overinflation rather than underinflation. Keeping the tires at the upper end of the recommended pressure range will keep those sticky buns from creating any more resistance than absolutely necessary.

Throttle sensitivity

The sensitive throttle (drive-by-wire on 2006 and newer S2000s) can ruin your gas mileage by easily letting you send more gas through the fuel injectors than you actually need to get the job done. I don’t have definitive data on this, but I’m willing to bet that the difference in fuel mileage from accelerating at 1/16 throttle is very different than 1/8 throttle. I’d love to hook up a real-time fuel flow meter to the car to test my theory sometime. If anybody reading this has done so with an S2000, I’d be very interested in hearing from you. (See below)

Into the unknown

Without a fuel-flow monitoring system, it isn’t clear which throttle settings for acceleration are optimal. I’ve heard that many engines are more efficient at larger throttle openings, yet I’m sure there’s an upper limit to this, especially on cars like the S2000 with VTEC and a higher power-to-weight ratio. Any data on this topic would be welcome.

Keep it fun

On a typical tank of gas, I may hypermile on one trip, then drive more aggressively on another. I didn’t buy my ‘S’ with the intention of coasting along with the engine idling, and if a stretch of twisty pavement opens up in front of me on a bright clear morning I’ll be the first to let my girl stretch her legs. For me, hypermiling is merely an alternative strategy for making driving interesting under what would otherwise be mundane circumstances. It’s another way to have fun with my car with the handy side benefit of saving a substantial amount of fuel. And for me, having fun is what driving a sports car is all about.