Vegetable oil could possibly be kinder to your engine, however, manufacturers are always very cautious about any modifications done to a vehicle and may well say it invalidates the warranty. Therefore, you can either wait until the warranty finishes (e.g. 3 years) or calculate the saving you will make on fuel over the 3 years warranty period, which may be enough to buy a new car (making any concerns not worth thinking about). If you have any concerns, you could check with your dealer, then let us know what they say.

It probably takes less time than it takes to drive to petrol forecourt, then queuing to get to a pump, hoping you get one with a pump on the right side of your vehicle, then queuing to pay, then finally driving back home again.

Of course with veg oil from home, you choose when you want to fill up and avoid queues and avoid getting wet if it starts to rain while you wait!  You could even fill-up in your dressing gown if you felt in a lazy mood.

If you buy vegetable oil there is no fuel duty on it. If you run your car on vegetable oil then Customs and Excise allow an allocation of 2,500L tax free, which if your car does 30 mpg will be equivalent to doing 16,000 miles per annum per address.  Which is a lot of saving. After 2,500L (which you should voluntarily declare) you are obliged to pay the requisite duty.  See the Customs and Excise website for further details. However, paying 50% less for Veg oil plus any duty payable, is still cheaper than what you would pay for fuel conventionally.