We’d been driving Jeeps for almost 22 years, until a month or so ago. Actually, just two of them, a ’94 Cherokee and a ’10 Patriot. The Cherokee, we essentially wore out, putting over one light-second on the odometer (300,000 km), and going through numerous windshields, a set of door hinges, grill, bumper, fender, hood, brakes, clutch, oil pump, power steering unit, several batteries, etc. over the 17 years we abused it. Our second Jeep was a “buy what they have on the lot, ’cause we’re leaving on a long trip and don’t trust the old one to get us there and back” affair, with no selection of color or features, or even model, as the newer Cherokees had gotten more expensive, and the Patriot was cheaper, on sale.
The Patriot was OK, in some ways a step up, with leather heated power seats, sunroof, six-speed auto tranny, and satellite radio; in other ways not so much. Despite a much smaller engine (2.7 l. versus 4.0 l.) it didn’t get much better fuel efficiency, though the old Jeep had dropped from a fuel burn of 9.8 l/100km to about 12.4 l/100km toward the end. During the nearly 200,000km we put on the Patriot in only five years, efficiency varied from 11.25 to 9.8 l/100km, admittedly at higher speeds, as the speed limits have gone from 90km/hr in 1994 to 125km/hr in the open plains of the west in the 2010s.
Faced with the possibility of expensive repairs and decreasing reliability, we decided it was time to look at a bit greener solution to our automobile needs. After a bit of research into hybrid gasoline/electric vehicles, we settled on the Ford C-Max, a “crossover” sized vehicle similar in capacity and form to our Jeeps–a five-door compact–but without 4-wheel drive. The attraction is the promise of fuel consumption as low as 5.75 l/100km and a range of 600-750km instead of 400-450km. Of course, “recharge” is the usual 5-minute tank fill.
The goal of hybrid technology is to reduce dependence on fossil fuels. At our current stage of energy economy, all-electric cars are not practical, as the battery technology, keeping the weight of the power train equivalent to the gasoline-powered designs, only provides less than 200km range, and requires several hours charging time, though higher-capacity batteries promise to increase range to 500km in some 2016 models. Also, recharging off the power grid means that all-electric cars are essentially mostly coal-powered, so do not solve the carbon-pollution problem.
The hybrid, then, is fundamentally a gasoline-powered vehicle with a sophisticated energy-management system that employs a relatively small battery and an electrically-assisted power train. The efficiency comes from using a relatively small gasoline engine that needs an assist for acceleration but is large enough to recharge the battery during low power demands. The braking system and transmission also serve to recover the kinetic energy of speed as battery charge when slowing and stopping. The engine shuts off when there is no power demand, i.e., when coasting downhill, and there is no idling at stops or in stalled traffic. While advanced computer software makes all of this possible, high efficiency is only feasible if the driver uses best operating practices. To this end, the instrument cluster display helps teach efficient driving technique.
So it happens that we have become “road mopes,” accelerating ever so slowly and smoothly, slowing early for stop signs and signals, coasting to a stop, and generally avoiding rapid speed changes. I’ve done some of those things all my life when I feel pinched for gas money: when we lived on Vashon Island in the late 1980s and I worked in Poulsbo, a long commute, I used to shut the engine off at the top of the last hill before the ferry dock on the way home and coast three miles to the toll booth. So far, the techniques have paid off, with better than advertised highway mileage on the new car. In town, however, the steep hills of Shelton and the short distances we travel have not paid off. Since waste heat is minimal, on cold days, the gasoline motor runs to heat water for the heater and to be more efficient when power is demanded, so the electric motor component sometimes never engages during short rides, dropping the efficiency from 5.8 l/100km to 15.75 l/100km. We could have opted for the Energi model, with larger battery and plug-in recharge for better short-trip efficiency, but then, we have the problem of burning coal to recharge (though most of our power comes from Bonneville Power Hydro plants, which pose a different environmental issue) and the fuel cost of hauling the heavier battery on long trips. Overall, in the first 1000km, we have achieved an average of 6.3 l/100km, slightly better than the Honda del Sol we had from 1996 to 2011. On occasion, we’ve made it up our hill, albeit very slowly, on electric power, but the battery range under load is only a few hundred meters. Of course, it recharges during the next downhill run, but at the expense of gasoline to reheat the engine if it is cold.
In many ways, driving a hybrid efficiently through conscious energy management techniques is a lot like riding our bicycle–to be able to go long distances, limit sprinting and fast starts to traffic necessity, minimize braking, coast when you can, and keep the rpm’s up to maximize power output from a meager source, whether old legs or a small-displacement engine. Hybrids aren’t new, but weren’t practical until sufficient computing power was available in a small package to make the decisions necessary to run the engine only when needed for power or charging. Early models, without intelligent control systems, and all-electric drive motors, were like a portable power generator used at a construction site–the gasoline motor ran all the time, throttling up when the load increased, which didn’t increase efficiency all that much, since it continued to run at idle and created a lot of noise. Consequently, these kludges never made it to market.
So it goes. We have purchased a new cartop rack to carry our bicycle racks, but haven’t installed it, waiting for a baseline average so we can see how much the air drag cuts into our efficiency and for a time when we will be bicycling regularly. Unlike the Jeeps, we will not leave the rack installed for long trips when we don’t need it. We’re getting good mileage, but we could have done nearly as well with the standard cars by manually switching the engine off at stops and being much more careful to not accelerate or brake unnecessarily. But, those techniques don’t recover braking energy or promote shutting off the engine on downhill runs, so the hybrid, for now, is the most practical technology for optimal fuel efficiency.
But, we’ve also locked ourselves into another seven years of car payments in an age when Congress doesn’t feel we deserve a cost-of-living increase, despite increases in housing and food costs, and increased medical costs with possibility of decreased Medicare coverage. For now, fuel costs have dropped, again, but will inevitably rise as production of fossil fuels drops, as it must, to reduce carbon output. Nevertheless, we want to set an example, however small, to the next generation that, in the face of irreversible man-caused climate change, we must try to avert total catastrophic runaway conditions. It may be too late: massive releases of methane from thawing hydrates in the Arctic tundra and ocean shallows are accelerating, compounding the rise in C02 levels. But, responsible carbon use can buy a little time, for possible, unknown technological solutions.