Hypermiling has more in common with race driving than you might think.
Hybrid power has been a polarizing point in the automotive community for more than a decade. Hybrid technology theoretically should offer levels of efficiency unmatched by any gasoline engine on its own, but it often doesn't. When the BBC's "Top Gear" program tested hybrid tech, they found that a Toyota Prius driven around a racetrack at race speeds got 2 mpg worse economy than a 400-horsepower BMW M3 driven at the same speeds. The lesson: Hybrid technology can offer returns in efficiency only if the driver knows exploit the powertrain's inherent strength while avoiding its weaknesses.
Instructions
1. Accelerate gently to your cruising speed, never using more of the throttle than you would need to maintain about 60 mph under cruise. This comes to about 50 percent throttle (half of the throttle pedal's travel) on most hybrids, but the idea is to keep the car running on pure electric power as much of the time as possible. The electric motor converts stored energy to movement with about 80 percent efficiency; the gas motor will do so at less than 35 percent efficiency.
2. Maintain momentum at all costs. Momentum equals energy expended to create movement, which translates to fuel burned and dollars spent. Brake as little as possible. Hybrids use regenerative braking to recharge their batteries, but regenerative braking will not recapture more than 50 percent of the energy expended to accelerate, resulting in a net energy loss of at least 50 percent under even the best conditions.
3. Increase your following distance (distance to the car ahead of you) to reduce the number of times you must respond to their movements by braking. Coasting in response to changes in speed requirements is far more efficient that hitting the brakes. Set your cruise control no higher than 55 mph; you'll lose about one mpg for every mile per hour over that, due to aerodynamic drag.
4. Use a racing style out-in-out technique to corner. When approaching a corner, swing as far away from the corner as possible while staying in your lane. Identify the apex of the corner, which is just past the center-point of its inside arc. Brake only as much as you need to in order to turn in and clip that apex point. Once you pass the apex, coast back to the outer part of that lane in a mirror image of your entry arc. Do not get back on the accelerator until you're almost completely straightened out, or you'll lose efficiency through excess lateral tire friction.This "fast-in-slow-out" technique is a bit backward from typical racing methodology (which is slow-in-fast-out), but will benefit you more where fuel economy is concerned since the lateral forces are absorbed during braking and coasting rather than during acceleration.
5. Brake while driving down steep hills, but coast down gentle slopes; try to keep your downhill braking speed just below the gas engine's engagement speed. This will put the regenerative braking motor at its maximum rpm for the greatest amount of battery recharge without wasting the braking friction with the gas engine. Allow the regenerative braking motor to absorb as much of the braking force as possible to get the highest recharge.
Tags: regenerative braking, about percent, braking motor, energy expended, Hybrid technology
