Diesel cars have long been popular in mainland Europe due to lower tax on diesel fuel, and since the UK's 2001 decision to tie Vehicle Excise Duty rates to carbon dioxide emissions, diesel's lower CO2 output has also made the fuel hugely popular to British buyers.
But with continued innovation in petrol engine design, growing concerns over diesel pollution, and 2017's UK car tax shake-up set to negate diesel's tax advantage here, are the days of diesel numbered? Here are five compelling reasons to spec your next car with a petrol powerplant.
01 Lower upfront cost
With all that extra emissions management tech, as well as the requirement for heavy-duty components to withstand their higher torque, diesel engines aren't cheap to make.
You can expect to fork out an extra £1000-£3000 for a diesel car versus one packing a similarly potent petrol engine, and though fitting the latter with a turbo and intercooler narrows the price gap, comparable diesels still tend to be pricier.
Pay £1000 more for your diesel engine and you’ll need to cover around 36,000 miles before that extra initial outlay is recouped by fuel savings, and that’s not even factoring diesel’s typical price premium at UK pumps.
02 Fewer complications
Tightening international emissions regulations have forced vehicle manufacturers to come up with new ways of reducing diesel's tailpipe nasties.
The Diesel Particulate Filter traps particulate matter and then burns it away using heated exhaust gas, but with temperatures of at least 350 degrees Celsius required, drivers who don't regularly reach high enough speeds to generate this heat risk filter clogging.
And even when regeneration is successful, DPFs have been known to clog over longer periods, requiring specialist costly cleaning.
Modern diesel engines can also be equipped with diesel exhaust fluid to reduce nitrogen dioxide emissions, though this urea-based solution will need topping up during a service, adding additional expense.
03 Save the world
Diesel – in the UK at least – has long been considered greener than Caroline Lucas dipped in mushy peas, with car manufacturers keen to christen their fuel-saving oil-burners with names like GreenLine, Econetic and Ecoflex.
But while diesel motors emit around 15% less CO2 than petrols, this doesn’t tell the whole story. Nitrogen dioxide output can be anywhere from 4-20x that of an equivalent petrol engine, contributing to increased ozone layer damage and a greater susceptibility to respiratory diseases.
Then there’s particulate matter (the black soot that belches from accelerating diesel vehicles), which is up to 22x higher and is known to contribute to cardiovascular disease and lung cancer.
04 Turbo torque
Diesel's higher compression ratio traditionally results in more torque and better low-down pulling power. However, this is also hugely helped by the addition of a turbocharger to improve performance across a broader rev range, and modern petrol engines of all displacements are also now benefiting from turbocharged torque.
With a blower set to spool up at low RPM, boosted petrol motors can generate similar grunt to turbo-diesels, reducing the need to rev them hard when you need to get a move on.
Combine this with the lower physical mass of a petrol engine compared to a conventional iron-block diesel of equivalent displacement and you may also get the bonus of a higher power to weight ratio.
05 Better refinement
Start an older diesel car on a winter morning and you'd be forgiven for thinking it was ready to be hitched up to a plough. These days such agricultural roots are better muted, but cheaper diesel cars short on sound insulation will still rattle the eardrums considerably more than their petrol-powered siblings.
Petrol engines also tend to rev more smoothly and progressively, whereas many turbo-diesel engines can be all out of poke by 3500 RPM.
Finally, petrol engines are often easier to start when cold, as a diesel will require a couple of seconds to warm its glow plugs enough for ignition.