Toyota Hybrid vehicles are being undersold as vehicles that are more ‘fuel efficient and less polluting’. Whilst they are, this approach leaves Toyota a hostage to fortune as the pollution is purely emotive and the mpg obtained depends on the driver.
A driver new to a hybrid vehicle will tend to drive it as a conventional model and will compare the bold mpg figure on the dash with an ideal figure from the manual for their previous car. This will in many cases lead to disappointment as evidenced by comments on Prius egroups.
In essence the Prius is a ‘quality’ vehicle in that it aims to maximise the ‘value added to society’ from its creation, use and disposal.
What does this mean in plain English? Well it means that the fuel and pollution savings are far more than is first apparent for the following reasons
- In its creation the Prius uses the Toyota Production System created by Taiichi Ohno, this is recognised worldwide for its effective use of resources – known as lean manufacturing in the West. Whilst this attempt to minimise the embodied energy in the car does is not immediately reflected in the cost to the driver as they are paying extra for the technology, it certainly can be marketed as an extra feel good factor.
- In use the mpg figure is misleading as this does not change when the vehicle is stationary. In a journey from Cornwall, although it took 12 hours, the fuel used was the same as the normal six-hour journey (actual reading 61.1 mpg). In a conventional car the engine would have been running for the total time and emitting pollution for the total time.
- This was great but the vital point that I one does not see mentioned is that the engine was only running for a fraction of the 12 hours, with the attendant saving in mechanical wear and tear. In fact, although I have a car that has 30,000 miles on the clock, the engine has only done, perhaps 20,000 miles – all under the control of the system, with no strain placed on it by me. Over the life of the vehicle this must be reflected in considerable repair and replacement costs (hopefully!)
- As the engine is not running when stationary (AC permitting) personal comfort is also enhanced in standing traffic.
- Predictive driving also reduces considerably the wear and tear on the braking system.
These are personal gains but the ‘value added to society’ from the demand side management and reduction in energy used from fossil fuels is considerable and will increase greatly as the proportion of hybrids grows and more of the standing traffic is composed of hybrid vehicles.’
My letter in in The Engineer, July 2005