There are three official fuel- consumption tests: an urban cycle, said to be a good simulation of typical city driving conditions; a constant 90km/h (56mph); and the constant 130km/h (75mph) test.
Most car makers pull every trick they can to optimise the figures: the promise of good fuel consumption sells cars. Typically, they will select the best engine from the production line. There is reckoned to be a 5 per cent difference in normal manufacturing tolerances between the best and worst engines. The best motor for good fuel consumption is the one that gives the most torque (pulling power) at the lowest revs.
The manufacturer's test car is likely to be fitted with the brand of tyre that offers the least rolling resistance. (Customers rarely have a choice: they simply take the brand that happens to be on the car when it is delivered.) Then the tyres are pumped up as hard as possible to reduce friction. If the handbook suggests a range of pressures, the test car's tyres will be at the maximum one. Some tyre manufacturers quietly allege that some car makers recommend overly high tyre pressures in their handbooks, purely to get good government fuel consumption figures. But when the car is delivered to the punter, a lower tyre pressure will be used to provide a more comfortable ride.
And some test sites give better figures than others. Many manufacturers do their 'run-down' tests in warm climates, such as Spain or Italy, and ideally in the warmest possible weather. Hot air is thinner, and therefore has less aerodynamic drag.
According to one engineer I spoke to, the overall improvement, thanks to these tricks, can be as high as 10 per cent. The upshot is that these government fuel figures should be treated with suspicion, and used only as a rough guide when buying a car.
Another warning: never believe the 56mph fuel figure, which is the one nearly always quoted in the ads. You will never, ever replicate this figure in normal, everyday driving.
CAR CABINS are usually awful. Swathed in dark grey plastic or, when car makers are really bold, black, dark blue or even dark brown, they offer a sombre and depressing environment. The plastics employed are usually of the cheapest possible variety: thin, hard and nasty to touch. And the only splashes of colour to lift the gloom (no wonder so many drivers look morose behind the wheel) are woven, with precious little flair, into the seat
Even the new Renault Twingo, named the most innovative car of 1992 by Autocar & Motor magazine, is littered with penny-pinching disappointments. Its switchgear is bright green, big and quite rubbery: all positive signs. The seat fabric is purple, red and green. Yet the plastic trim that surrounds this coral reef is the usual North Sea grey.
The Twingo, though, is not the only sign of better times ahead. The new Ford Mondeo comes with a rather fetching tan-coloured dash, as well as the ubiquitous dark grey, black and dark blue. The Land-Rover Discovery was a real trend-setter: when it went on sale in 1989, its cabin hue was Cambridge Blue; a Mondeo-
like tan followed.
Grey interiors have become de rigueur over the past decade or so, because grey works with any exterior colour. Car makers have therefore been able to rationalise their trim colours, and save money. Never mind the gloom, watch profits boom] Never mind, either, that black and other dark colours show up dirt, and are hot and oppressive in summer.
Research in the United States has shown that the most restful colour for cabins is green. That is hardly surprising: green is redolent of the countryside. But it clashes with most exterior
These days, however, car interior designers are not only experimenting with brighter colours, they are also lobbying for the return of natural materials, or more natural-looking materials. Everyday cars of 40 years ago often had leather upholstery and wooden dashes and door trim; they had chrome-plated door handles, window winders and interior locks. So the cabin of a Fifties car was a much more appealing place to travel in than today's plastic and polyester cocoon.
At the recent Paris show, Volvo displayed a model with a startling yellow and purple dash, though that may be taking things a little too far. Its cabin was partly made from cork, and leather and suede-like materials are being used more and more. For me, the most attractive so far is Lancia's handsome Alcantara trim: it looks and feels like suede, but it is cheaper and easier to maintain.
Many Japanese car makers have already reintroduced 'chrome-plated' door handles; unfortunately, the chrome is all too obviously laid-over plastic. An engineering friend tells me that real chrome-plated metal door handles - lovely to touch, as well as to view - cost about pounds 1.50 extra per car. Why is no mass car manufacturer prepared to spend this sum on their low- to medium-range models?
TO MARK the 25th anniversary of the London-Sydney Marathon, first of the 'modern day' long- distance car rallies, 106 25-year-old cars will set off from Chelsea Harbour, London, on 17 April to drive to Sydney. The rerun, sponsored by Lombard, is a proper, competitive rally; the only oddity is that all the cars must be of a type available when the original event was held in 1968.
The 11,500-mile route takes cars through France, Belgium, Germany, Austria, Slovakia, Hungary, Romania, Bulgaria, Turkey, Iran, Turkmenistan and Uzbekistan where, in Tashkent, two Russian Antonov military cargo planes will carry the surviving competitors over the Himalayas to Delhi. The rally then heads south to Bombay, from where the Antonovs will fly the cars to Perth and a 3,500-mile dash to Sydney Harbour, where the cars should arrive on May 16.
I will be doing the event with my Dad in a Mk1 Ford Escort.