The car rental companies, fully cognizant of the opportunity and the problems, have been ready with a menu of programs and suggestions.
The car rental companies, fully cognizant of the opportunity and the problems, have been ready with a menu of programs and suggestions. Their most obvious tactic is the increase of fuel-efficient cars in their fleets. At last count, between them, Enterprise Rent-A-Car, National Car Rental and Alamo Rent A Car own more than 440,000 cars that average at least 28 mpg or better — more than 237,000 average 32 mpg or better. Hertz's Green Collection numbers more than 35,000.
New MPG Calculations
It's wise to keep sight of the difference between fuel efficiency and environmentally sound. The Environmental Protection Agency (EPA), in its SmartWay program, explains that fuel efficiency is just one thread in the whole fabric. Its ratings for SmartWay-certified vehicles are based on greenhouse gas scores, which include improved fuel economy as well as reduced levels of emissions that cause greenhouse gases. EPA also measures air pollution scores, which concentrates on the emissions that cause smog and health problems. (Learn more about the SmartWay program at www.epa.gov.) Greenhouse gas (CO2) and air pollution (NOx and NMOG) are both bad — both can leave you gasping for breath, just like those fuel costs — but they are not exactly the same thing.
With most consumers' focus right now more firmly on fuel economy than environmentalism, car rental companies (dealers too) have been touting that portion of their fleets that deliver 28 mpg or better. Comparing past mpg records with current ones became a little more complicated recently when the EPA changed the way it calculates fuel economy to account for vehicle-specific effects of high speed/rapid acceleration driving, use of air conditioning, and cold temperature operation. Under the new method, fuel economy estimates for 2007 and earlier models are lower than estimates originally in the government's fuel economy guide. The new numbers, cautions EPA, do not mean that carmakers are manufacturing less fuel-efficient models.
The real caveat is that, when it comes to fuel consumption, there's a difference between highway driving and city driving. Based on data from Prime Numbers Technology, there does not yet appear to be many corporate travel policy changes aimed at fuel economy, but if the day ever comes, travel managers will need to know what type of mileage their road warriors are racking up:
• highway miles: statistically a mixture of rural and interstate driving, longer trips (and therefore more miles in a more fuel-efficient warmed up engine) and at speeds faster than those usually driven in city traffic.
• city miles: miles accumulated in shorter bursts, in cars with cooler engines (EPA specifies "a vehicle started after not running for 12 hours"), and driven at slower speeds with a lot more time spent with the engine at idle.
Rules For The Road
For highway driving, drivers should think in terms of cruising even though they have the opportunity to go fast. Cruising keeps the RPMs down, decreases drag and optimizes the opportunity for fuel efficiency. "In fact," says Enterprise, "for every 10 miles per hour you reduce speed, you improve your fuel economy by 4 mpg ... You can improve your gas mileage about 15 percent by driving at 55 mph rather than 65 mph." Promote cruise control.
RPM levels — and fuel efficiency — are also optimized by smooth starts when traffic lights go green. "For automatic transmission vehicles," advises Enterprise, "accelerating gently prompts automatic gear shifting at lower engine speeds; with a manual transmission, … shift gears between 2,000 and 2,500 RPM."
At highway speeds, it won't work to turn off the air conditioning and roll down the windows to save fuel — that increases drag and, well, drags down fuel efficiency. It will work in the city, however, when drag is not much of a factor in the first place.
City driving just naturally increases gas consumption because it involves more start-and-stop driving than the open road does. When possible, drivers should avoid heavy traffic and road construction — rental car counter agents are often able to help with that, pointing out where and when there's likely to be trouble.
Again driving smoothly helps conserve fuel but in city driving it's more of a balancing act. Enterprise's fleet management division advises that drivers turn off the engine if it looks like they're going to be held up for more than a couple of minutes: "Two minutes is generally the balance between how much fuel is used idling compared to the amount of fuel required to restart the vehicle."
It's also smart to buy the right fuel at the right price, points out Enterprise, which is a big proponent of E85 (85 percent ethanol and 15 percent gasoline), based on its reduction in greenhouse gas emissions. But the company also points out that most gasoline-driven fuel cars don't need top-dollar premium fuels
Another Change
The definition of "the right fuel" has been further altered by Hertz's new refueling program, launched July 1. On that date, it began basing the price of fuel offered at its rental locations on the local markets, plus a one-time refueling fee of $6.99 for rentals that are being returned. Those who purchase fuel when they pick up their rentals will also be paying market-rate prices, minus a discount of about 15 cents per gallon. The new program promotes fuel economy by eliminating mileage sometimes spent in hunting down a cheap off-airport gas station. And finally, regardless of where renters choose to take their cars, it pays to keep the load light — for exactly the same reasons that the airlines have instituted baggage fees: the more weight to carry, the more fuel that's needed.