Investing in oil instead of filling up the car would have delivered a 34% return in the past six months. But can oil price rises continue and how should you invest?

The price of a barrel of crude has hit all-time highs of more than $140 a barrel since the turn of the year.

If a motorist had taken the £60 cost of filling up once a fortnight, from January to the end of June, and placed it in a fund tracking the price of oil instead, they would have seen handsome profits.

With a £60 fill-up every two weeks, in the first six months of 2008 the typical family car would have used £780 worth of fuel.

If a driver had ditched the motor and taken that £780 and invested it in the ETFS Securities Brent 1 Month exchange traded fund, it would have rocketed by no less than 34% to £1,034, over the same period.

But after peaking last week, prices of oil have slipped back and been flatter over the past seven days. US crude has remained near $135 a barrel and at one point oil fell as low as $132, more than 10% below the record $147.27 reached on 11 July.

Overall the price of oil has been on an upward trend for more than six years now - the longest period of rising prices on record.

Train and bus operators are enjoying a surge in popularity as high oil prices push commuters out of their cars and into public transport.

Statistics from the Department for Transport indicate the rate of car usage has fallen every quarter in the last year from a high point of annualised growth of 4% seven years ago.

While a more environmentally-friendly demographic may be emerging in the UK, the soaring cost of oil is undoubtedly a major motivator.

And despite slight falls in the use of oil in the UK and US, developing economies are predicted to continue to fuel higher demand for years to come.

Tony Hayward, chief executive of oil giant, BP, recently said: 'The defining feature of global energy markets remains high and volatile prices, reflecting a tight balance of supply and demand.'