ross finlay considers how the source of power is changing

As more people toy with the idea of converting to low-cost LPG fuel, the Vauxhall Astra comes into play. Vauxhall was the first UK car company to move seriously into dual-fuel cars able to run on either unleaded petrol or Liquefied Petroleum Gas, and to offer them with a full manufacturer's warranty.

LPG conversions cost money, of course, but up to 75% of the price can be reclaimed under the Government-backed Powershift programme, although the cashback deal applies only to new or year-old cars.

The Astra isn't just a pioneer of dual-fuel running. It offers by far the biggest range of individual models converted as from new. There are something like 20 of them in the catalogue, from three-door and five-door hatchbacks, to estate cars and vans.

In fact, the Astra is built on a scale it's often easy to underestimate. When you take Vauxhall and Opel production together, this is one of the top-selling model ranges in Europe, and the Astra is the runaway leader of the UK estate car sales league, a position it has held for several years.

The styling department didn't quite ring the bell with the Astra, which seems to me to look much better as an estate than it does in hatchback form. In fact, one of the most attractive versions I've ever driven, crazy though this may sound, was a red Astravan.

One thing to bear in mind, though, is that this is an aerodynamically satisfactory design. Astras have lower drag coefficients than many of their rivals, and the body is also better protected from the elements and the rust bug than it used to be. The latest cars come with a 12-year anti-perforation warranty.

Most recent addition to the range, the Astra coupe, carries on the general styling theme of the other cars but isn't built in an ordinary General Motors factory. Bertone was the design partner, and the car is produced in its factory in Italy. The coupe is rather colour sensitive, and it has a modified interior, but when you see one with a colour scheme which suits it, this is a pretty handsome machine.

A strong element in the mainstream Astra range is the great variety of individual models it offers, although Vauxhall has trimmed the number down from the days when there were sixty-odd variants. There are Envoy and Expression models at the low end of the scale, and Club models are available too, as well as the more familiar LS, SXi, SRi, CD and CDX. These last two often attract customers ''downsizing'' from a more expensive class, and the CDX in particular is very well presented and equipped.

In the middle stages of its production life, the Astra certainly isn't stagnating. Like other model ranges, it's in the process of benefiting from Vauxhall's major engine upgrade programme.

This is a two-part affair. One element in it is a series of power boosts for existing engines. The 1.6-litre petrol engine used to have 73bhp, and that's now up to 83bhp. Similarly, the 1.8-litre 16-valve goes from 112bhp to 122bhp. Other petrol engines get the same treatment, but at the same time they record lower exhaust emissions.

But there are all-new engines too. The coupe was introduced with a 1.8-litre engine. Soon there will be a 2.2-litre aluminium engine for it as well, and that will also appear in the hatchback.

A two-litre turbocharged engine is due to power the top-rated Turbo Edition coupe. It will peak at a hefty 186bhp and sprint the car to 60mph in under seven seconds. The Turbo Edition will be launched at the Birmingham Show, finished in a mean-looking carbon black colour scheme. This is the first standard production Vauxhall (which means not including the late lamented Lotus Carlton) with a test track maximum over 150bhp.

However, the Astra does pretty well in diesel applications too. There are direct injection 1.7-litre and two-litre sizes, with far better performance, economy and emission levels than the earlier indirect injection types. The 1.7DTi has an extra urban economy test figure of just over 70mpg.

Astra owners looking for a sportier appearance and low-slung suspension can browse through the catalogue of Irmscher special parts. The German tuning and accessory firm offers items like alloy wheels, spoilers, interior trim kits and lowered suspension - all official Vauxhall parts which can be specified from new.

From a sporting point of view, this isn't mutton dressed as lamb. Vauxhall was the top manufacturer in this year's Mobil 1 British Rally Championship with a team of Astras, and the Astra will take over from the Vectra as the company's entry in next year's revised British Touring Car Championship.