Ask Joe Mechanic: Alternative Energy Vehicles - Part 3A

This week and next week we will point out some of the positive and negative facts about hybrid vehicles including fuel efficiency, emissions reductions, environmental impacts of the hybrid battery, costs and availability of raw materials, and pedestrian safety concerns.

The first two items, fuel efficiency and emissions reductions go hand-in-hand, so we will discuss them together.  The hybrid vehicle typically achieves greater fuel economy and lower emissions than conventional internal combustion engine vehicles (ICEVs), resulting in fewer emissions being generated. These savings are primarily achieved by three elements of a typical hybrid design:

1. Relying on both the engine and the electric motors for peak power needs, resulting in a smaller engine, sized more for average usage rather than peak power usage. A smaller engine can have less internal losses and lower weight.
2. Having significant battery storage capacity to store and reuse recaptured energy, especially in stop-and-go traffic typical of the city driving cycle.
3. Recapturing significant amounts of energy during braking that are normally wasted as heat. This regenerative braking reduces vehicle speed by converting some of its kinetic energy into electricity, depending upon the power rating of the motor/generator.

Other techniques that are not necessarily a ‘hybrid’ feature, but that are frequently found on hybrid vehicles include:

1. Using Atkinson cycle engines (reverse rotation) instead of Otto cycle engines for improved fuel economy.
2. Shutting down the engine during traffic stops or while coasting or during other idle periods.
3. Improving aerodynamics: (part of the reason that SUVs get such bad fuel economy is the drag on the car. A box-shaped car or truck has to exert more force to move through the air causing more stress on the engine making it work harder). Improving the shape and aerodynamics of a car is a good way to help better the fuel economy and also improve handling at the same time.
4. Using low rolling resistance tires (tires were often made to give a quiet, smooth ride, high grip, etc., but efficiency was a lower priority). Tires cause mechanical drag, once again making the engine work harder, consuming more fuel. Hybrid cars may use special tires that are more inflated than regular tires and stiffer or by choice of carcass structure and rubber compound, have lower rolling resistance while retaining acceptable grip, and so improving fuel economy whatever the power source.
5. Powering the air conditioning, power steering, and other auxiliary pumps electrically as and when needed. This reduces mechanical losses when compared with driving them continuously with traditional engine belts.
   
   These features make a hybrid vehicle particularly efficient for city traffic where there are frequent stops, coasting and idling periods. In addition, noise emissions are reduced, particularly at idling and low operating speeds, in comparison to conventional engine vehicles. For continuous high-speed highway use these features are much less useful in reducing emissions. 

Hybrid vehicle emissions today are getting close to or even lower than the recommended level set by the Environmental Protection Agency (EPA). The recommended levels they suggest for a typical passenger vehicle should equate to 5.5 metric tons of carbon dioxide. The three most popular hybrid vehicles, Honda Civic, Honda Insight and Toyota Prius, set the standards even higher by producing 4.1, 3.5, and 3.5 tons showing a major improvement in carbon dioxide emissions. Hybrid vehicles can reduce air emissions of smog-forming pollutants by up to 90% and cut carbon dioxide emissions in half.

As regarding the environmental impacts of the hybrid battery, the industry is still in the learning stage. What has not totally been developed yet is the full technology for recycling of spent hybrid batteries because of their relative newness. While we do know that they are more environmentally friendly than the conventional lead-acid vehicle battery, that battery has a well-established recycling process in place for many years.  The conventional battery has its problems with controlling lead emissions. Today most hybrid car batteries are either nickel metal hydride or lithium ion. Of the two, the lithium ion has the lower toxicity.

We will continue this battery discussion and more in next week’s column.
Recent recalls:
374 2013 Dodge Dart
Vehicles equipped with the Mopar 13 trim package. In the affected vehicles, the front seat mounted side airbags (SAB) may not have been properly installed into the seat. In the event of a crash necessitating SAB deployment, the SABs may fail to deploy as intended, increasing the risk of injury.

2,608 2007-2009 BMW F 800 S and F 800 ST motorcycles
Due to incorrect tolerances, the rear wheel drive bearing and rear axle may wear. Bearing and axle wear may affect handling and control of the motorcycle, increasing the risk of a crash.

130 Mercedes-Benz 2013 SL63, SL550, and SL65
The affected vehicles are equipped with an occupant classification system (OCS) that may not detect a very light person sitting in the front passenger seat. If the OCS does not detect a very light person sitting in the seat, the passenger side air bag would be turned off.  In the event of a crash necessitating side air bag deployment, the passenger would be at an increased risk of injury.

2,475 BMW 2012 K1600 GT and K1600 GTL motorcycles
In certain riding conditions, an incorrect throttle valve control signal may be received by the engine control unit, limiting the engine speed. As a result of the reduced engine speed, the engine could stall, increasing the risk of a crash.

22,483 Harley-Davidson 2014 FLHTCUTG, FXSBE, and FLSTNSE FLHTCU, FLHTK, FLHTP, FLHX, FLHXS, FLHTKSE, and FLHRSE motorcycles
The affected motorcycles may have been built with an incorrect clutch release plate. Additionally, The clutch master cylinder may allow air into the clutch system. Either condition may prevent the clutch from disengaging. If the clutch does not disengage, the rider may have difficulty slowing or stopping the motorcycle, increasing the risk of a crash.

If you own one of these vehicles, contact your local dealer for further instructions on how to proceed.