The weekly segment where I answer your car questions (and pull the pants down on my nut of the week)

This week's questions

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Dr David Bowman pleads for his life with Hal, the computer, in  A Space Odyssey . Oddly enough, this could be you in your robot car in the near future

Dr David Bowman pleads for his life with Hal, the computer, in A Space Odyssey. Oddly enough, this could be you in your robot car in the near future


What are your thoughts on autonomous cars? Self-driving cars? I think as soon as there’s an accident and someone is killed the manufacturer will be sued and they will scrap all plans. - Astra

Who can forget Dr David Bowman from Stanley Kubrick's epic 2001: A Space Odyssey? The scene where he begs for his life with the Hal 9000 computer that has decided he's expendable - better off dead. "Open the pod bay doors please, Hal," says Dr Bowman - chilling, by virtue of the utter emotional neutrality of the exchange. Oddly enough, this might not be too far from the truth with robot cars in the near future. Watch the video to see why your robot car might be programmed to kill you. 

The technical problems with autonomous cars remain, but the moral, ethical and legal landscape is as yet unresolved.

When the Santa Cruz concept is productionised and sold here, Hyundai will be the number 2 carmaker in Australia

When the Santa Cruz concept is productionised and sold here, Hyundai will be the number 2 carmaker in Australia


How come Hyundai doesn’t sell a ute? - Jim

Basically, this is because they've been overclocking their R&D and production capability for about a decade to satisfy demand, and something's gotta give. Ute design and production has been glaringly on the back burner. But thanks to pressure from Hyundai US - the Santa Fe-based Santa Cruz pickup concept from last year’s Detroit Motor Show appears to be getting the green light for production this November.

If Hyundai manages to sell 10,000 utes (that's less than the Mazda sells with the BT-50) it’ll nudge Holden and Mazda to the side and Hyundai will take second spot on the sales podium below Toyota. That’ll get people talking. Hyundai has been amazingly receptively been embraced in vans (currently iLoad is the #2 van behind Hiace).


Last week you compared petrol and diesel. Since they all come from crude oil, why does the price of diesel fluctuate independently of the price of petrol? - Karen

1 barrel of oil is 159 litres (that's 42 US gallons). It produces:

  • 73 litres of petrol
  • 38 litres of diesel
  • 16 litres of jet fuel
  • Sundry other petrochemicals

This is a fairly rigid relationship - basically you tip in a barrel at one end of the refinery, and this is what you get out the other end.

So, given that supply is more or less the same (of the raw material) for both petrol and diesel, the demand side of the equation is what drives the differences in prices. Basically petrol is the mass transit fuel, and diesel is what industry and agriculture runs on. So the price of petrol is driven by demand for mass transit, which the price of diesel is driven my industrial demand - which tends to like directly to boom and bust cycles of the economy. Diesel typically is depressed when economies do badly, and it tends to be expensive when economies surge ahead.

Should you buy a petrol or diesel car? Find out in this report >>

It's a mistake to scrimp on servicing - even if you don't drive very far

It's a mistake to scrimp on servicing - even if you don't drive very far


I don’t drive very much, and my Subaru has six-month/10,000-kilometre servicing. I’d be lucky to drive half that distance every six months. Do I still need to get my car serviced on time? - Tina

Carmakers impose a time interval on servicing for vehicles that don't cover much distance because time affects some components - typically little use (low kilometres) is hell on earth for engine oil. So, even if you don't drive far, a service at the time interval is still necessary. Obviously, if you drive long distances, the distance interval will pertain. It's a huge mistake not to abide by the service interval.

However, with many manufacturers moving to 12-month time intervals for servicing, and some still dragging the chain at six, you have to ask why. Obviously, metallurgy and lubricant technology is constant across the entire industry, so are those still dragging the chain remaining at six months because there's a valid engineering justification, or are they just doing it to maintain dealer profits at current levels? (Servicing is a significant profit centre for dealership operations...) Only time will tell.

See how to cut servicing costs and preserve your warranty >>

2015 Mazda BT-50 4X4

2015 Mazda BT-50 4X4


I am possibly in the market for a new BT-50 ute. I'm looking at both the 4x2 and 4x4. I’ve been told that the traction control on these is that good that you really don't need the 4x4 system when going off road. Is this true? I want to drive some off road tracks as well as sand dunes. Please help! - Jarryd

Traction control is not a substitute for 4WD. If manufacturers could offer off-road capability without putting in all that extra hardware (at significant cost) then that's what they'd do. If all it took was traction control, off-road utes would be a lot cheaper. 

If you bought a hi-rider 4X2 it would have good ground clearance and certainly the traction control will help improve its abilities on (say) a slippery track. It will assist in reigning in wheelspin. However, there are times when you need both ends driving (especially on sand dunes and in other serious off-road driving). So if it was me I’d have a think about the style of driving you are going to do. If they are simple off-road tracks (like farm tracks) then 4X2 with good ground clearance might be enough (and you’ll save money). However, if it’s also soft sand, mud and challenging tracks requiring a lot of suspension travel then I’d go for 4X4 (and the traction control will help with 4X4 as well). Bear in mind the other thing you don’t get with 4X2 is a low-range gearset, which is essential for rough terain where slow speeds are required.

Interested in a new BT-50? Check out my Mazda BT-50 review >>


I’m not sure which is better: the Carnival, Odyssey or C4 Grand Picasso - Graham

From left to right (above): Kia Carnival, Honda Odyssey and Citroen Grand C4 Picasso (click to enlarge)

In a nutshell:

  • Kia Carnival - the pick of the bunch. Excellent value (but not cheap). Superb warranty and servicing arrangements. Brilliant features and versatility. My advice? wait for the structural engineering (currently under way) revision to deliver a a five-star ANCAP safety rating. Check here >> Easily outpoints the other two on key objective and consumer criteria.
  • Honda Odyssey - ugly and outdated. Poor warranty and servicing schedule. The price would want to be right. Honda has been asleep at the wheel for about 10 years.
  • Citroen Grand C4 Picasso - brilliant design and versatility, but held back by the brand's poor popularity, and vestigial Australian footprint.