Hostage to fortune

Mike Antonis (Diesel beats hybrids - The Engineer, June 14)  may well be right about the possibilities of semi-hybrid technology — but to dismiss the Prius out of hand is a little premature.

Using the spectre of reported stalling is also underhand, even if true — how many IC powertrains failed in motoring’s early days?

Driving under varying conditions I normally manage around 61mpg; however, I concede that when driving flat out on a motorway the gain, if any, is marginal. The technology is not magic, but we need it — especially the electronics and drive — if cars are ever to evolve to fuel cell vehicles.

I have driven a Prius for 30,000 miles, and following a 12-hour journey from Cornwall and reading a letter on road charging in the national press stating that congested roads add 50 per cent more pollution than uncongested ones, I wrote to Toyota, extracts of which I enclose.

As the owner of a Prius for  well over a year I feel the Toyota hybrid vehicles are being undersold as vehicles that are more “fuel efficient and less polluting”. This approach leaves Toyota a hostage to fortune as the pollution is purely emotive and the mpg obtained depends on the driver.

Motorists new to hybrids tend to drive them as conventional models and will compare the bold mpg figure with an ideal figure from the manual for their previous cars. This will in many cases lead to disappointment.

The Prius is a “quality” vehicle that aims to maximise the “value added- to-society” from its creation, use and disposal. Put simply, the fuel and pollution savings are far more than is first apparent, for these reasons: The Prius uses Toyota’s production system created by Taiichi Ohno, recognised worldwide for its effective use of resources — known in the West as lean manufacturing.

While this is not immediately reflected in the cost to drivers, as they are paying extra for the technology, it can be marketed as an extra feelgood factor.

In use, the mpg figure is misleading as this does not change when the car is stationary. On my Cornwall journey the fuel used was the same as the normal six hours taken (actual reading 61.1 mpg). In a conventional car the engine would have been running and emitting pollution for the total time.

The vital point is that the engine was only running for a fraction of the 12 hours. So, although I have a car that has 30,000 miles on the clock, the engine has only done, perhaps, 20,000 — all under the control of the system.

Over the life of the vehicle this must be reflected in considerable repair and, hopefully, replacement costs.

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.

With respect to end-of-life disposal, Toyota has strategies in place. But disposal should arrive later due to less wear and tear; especially if the company starts to sell hybrid mobility rather than the vehicle.

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 as the proportion of hybrids grows.

Derek Deighton

Oswaldtwistle

Lancs