You might be considering changing your petrol-powered car to a diesel model as fuel prices hit an all-time high and look set to rise even further.
Fuel efficient diesel-engined cars are looking like a smart choice: the share of diesel sales rose to a new record of 46.1% in 2010 and it's highly likely they could eclipse their petrol counterparts in the months to come.
There are drawbacks with diesels though. Although average economy is also (usually) rated better than the equivalent petrol model, a diesel will carry a premium over petrol equivalents when you come to buy. In some cases that means you'll have to travel many miles before it starts to pay off.
Below are two tables outlining a selection of ten models that have both diesel and petrol equivalents in their range. We have detailed how much more you will pay for a diesel model and how many miles you will have complete at current fuel prices before you recoup your money if you are travelling an average of 12,000 miles a year. The two tables comprise diesel versions that get the Parkers thumbs-up and diesels that get the Parkers thumbs-down.
Our table shows that if you opt for a diesel Chevrolet Captiva, costing more than £5,000 than its petrol equivalent, it will take 15 years to recoup your money in fuel savings, which is clearly an unwise choice. Conversely, a Saab 9-5 diesel is both cheaper to run and buy so you'd be a fool to opt for a 9-5 petrol model.
Check out our comparisons below:
Diesels that get a thumbs-up
| Petrol model | Diesel model | Diesel premium | Miles to break even | Time to break even |
| BMW 523i SE | BMW 520d SE | -£3,270 | N/A | N/A |
| Saab 9-5 Saloon 2.0T Vector SE 4dr | 2.0 TiD Vector SE4dr | -£1,795 | N/A | N/A |
| Peugeot 3008 1.6THP (156bhp) Exclusive 5dr auto | 1.6HDI Exclusive 5dr EGC | £154 | 2,749 | 84 days |
|
Merc E-Class saloon E250 CGI BlueEfficiency Auto SE 4dr |
E220CDI BlueEfficiency Auto SE 4dr | £110 | 3,463 | 105 days |
| Volvo XC60 T5 (240bhp) SE 5dr Powershift | 2.0 D3 (163bhp) DRIVe SE Premium 5dr | £547 | 11,349 | 345 days |
*The Saab 9-5 and BMW 5-Series diesel models are both cheaper to buy and run compared to the petrol equivalent.
Diesels that get a thumbs-down
| Petrol model | Diesel model | Diesel premium | Miles to break even | Time to break even |
| Toyota Avensis Tourer 1.8 V-matic T4 Nav 5dr | 2.2 D4-D T-Spirit Nav 5dr | £4,115 | 228,145 | 19 years |
| Chevrolet Captiva 2.4LS 5dr 7seats | 2.0 VCDi LT 7 seats 5dr | £5,265 | 180,584 | 15 years |
| Nissan Qashqai 1.6 Acenta | 1.5 dCi Acenta | £1,700 | 96,343 | eight years |
|
BMW 320i SE (08) 4dr |
320d 184bhp) SE 4dr | £2,120 | 66,534 | Six years |
|
MINI 1.6 3dr |
1.6 D 3dr | £1,080 | 35,387 | Three years |
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