LIFE with our bi-fuel Volvo V70 has become substantially more interesting in the past fortnight, with both good news and bad affecting impressions of the clean emission car.

On the plus side, finding gas is proving more straight- forward than first impressions suggested, and now I've developed the habit of filling up every 200 miles, I'm running on gas for more than 90% of the time and getting to know the staff at my local forecourt rather well.

At an average of 38 pence per litre, I'm effectively enjoying half-price motoring compared to the equivalent petrol model, which should endear me to the company accountant when driving on business and to my bank manager for my private mileage.

Add in the feelgood factor of going green in the aftermath of the Johannesburg Earth Summit, and the seesaw between the inconvenience of frequent fill-ups and the halo of good citizenship is definitely on the up.

But it's not all plain sailing, and I've had more than a couple of anxious moments behind the wheel of the Bi-Fuel. The problem seems to appear when the LPG tank has been run to empty and then filled-up. When the engine is restarted, it fires up in petrol, but when the technology switches automatically to gas, the LPG does not seem to reach the combustion chamber. Consequently, the car loses power immediately and could slow to a complete standstill unless I flick the switch to resort to petrol power.

The first time this happened I was on a fast-moving dual carriageway, hardly the ideal place to coast to a standstill, and it has happened since.

The problem does rectify itself after about 10 minutes – perhaps the valve that switches between petrol and LPG is just a bit stiff – but it's disconcerting to say the least, and is also damaging the amount of time I've spent running on gas.

There's also a noticeable decline in torque when running on gas, although with the environment in mind I should put my appetite for lively acceleration to one side.

My second concern is the absence of a spare wheel. Travelling alone on business I'm prepared to take a gamble that I'll avoid punctures and that the aerosol repair kit will enable me to limp to a fast-fit centre if I do suffer a flat.

But a Volvo estate is also a family car, and when its on domestic duty I do have concerns about being stranded with wife and baby aboard.

Like all insurance policies, I hope I never suffer a flat tyre, and in 15 years of driving it's only happened once.

But insurance is for the bad times, and I'd prefer a policy that included a spare wheel.

Bi-fuel aside, the V70 continues to offer comfortable, safe and secure transport with the flexibility of a wonderfully large boot.

As an estate car I'd recommend it for every short list, but unless you drive regularly into central London and are looking for a car to avoid the £5 per day congestion charges, I'd have to say that the V70 D5 diesel or even the petrol version would be an easier model to live with.

Company car tax bill 2002 (40% tax-payer): £167 per month