Details for Potential Fuel Savings Generated by a National Speed Limit
| Property | Value |
| Name | Potential Fuel Savings Generated by a National Speed Limit |
| Description | For a vehicle traveling at high speed, reducing its speed increases
fuel economy. In general, at speeds over approximately 35 to 45 mph, if
a vehicle reduces its speed by 5 mph, its fuel economy can increase by
about 5 to 10 percent, because air resistance, or drag, increases
exponentially as a vehicle goes faster. Conversely, air resistance
diminishes more rapidly as a vehicle slows down, thus increasing its
fuel economy. According to existing literature and knowledgeable
stakeholders, there is no single speed that optimizes fuel economy for
all vehicles. Optimal speed for fuel economy for individual vehicles
ranges widely, but is generally between 30 and 60 mph, depending on a
vehicle's characteristics. However, a vehicle's fuel economy also
depends on other factors besides air resistance. Factors that enhance
fuel economy include engine efficiency enhancements (e.g., fuel
injection), electronic and computer controls, more efficient
transmissions, and hybrid technology. However, other factors decrease
fuel economy. In general, over the last 2 decades, fuel economy gains
resulting from advances in automotive technologies have largely been
offset by increases in vehicle weight, performance, and accessory
loads. Specifically, vehicles are heavier than in the past, because
they are larger and include more technologies. Further, increased
accessory loads, such as air conditioning and electronics, have also
reduced fuel economy. According to EPA, from 1987 through 2004, on a
fleetwide basis, technology innovation was utilized exclusively to
support market-driven attributes other than fuel economy, such as
performance. Beginning in 2005, however, according to EPA's analysis of
fuel economy trends, technology has been used to increase both
performance and fuel economy, while keeping vehicle weight relatively
constant. Lowering speed limits can potentially reduce total fuel
consumption.
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| Filename | gao_warner_response.pdf |
| Filesize | 266.6 kB |
| Filetype | pdf (Mime Type: application/pdf) |
| Creator | Drive55 |
| Created On: |
11/17/2008 20:23 |
| Viewers | Everybody |
| Maintained by | Editor |
| Hits | 1691 Hits |
| Last updated on |
11/17/2008 20:26 |
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