Want to save on consumption? Here's how to drive... and how not to...

Hello Petrol Head,

I have been religiously reading your column since inception and must admit that you're doing a splendid job. My question today is about fuel consumption.

1. Does it really mean that a 1500cc is more economical than an 1800cc + given that both are serviced at the required intervals?

2. What is the best way to optimise consumption?

3. What is the best rev to maintain in highway driving to achieve the best results?

Thanks.
Gillian.

Hi Gillian,

I have written about this in depth before, but since you asked, here we go.

1. The 1500 is more economical than an 1800 keeping all factors constant, but factors are never constant, are they? As I often point out, the biggest contributor to fuel consumption is the very act of driving.

a) How you do it matters more than what you are doing it with.

b) Then we have where you are doing it, and not just in traffic either. Going uphill could easily favour the bigger engine over the small one because it doesn't need to be revved as hard to tackle the incline.

c) This also applies to vehicle occupancy, human and non-human. When fully laden, vehicles with bigger engines will fare better than their smaller-engined counterparts

2. The best way to optimise consumption is to not drive at all. I have mentioned this before.

However, man must move, and so many times that movement involves driving, so the tips will be forthcoming.

a) Drive gently, not slowly. Slow driving also pushes consumption up. Gentle driving means don't stomp either the accelerator or the brakes, just feed the power in smoothly when adding speed, and take your foot off the accelerator to coast within part of your braking distance rather than braking through the entire space. When you brake, the kinetic energy that was spent accelerating the vehicle is wasted as heat energy from the brakes. A corollary to this is "don't brake", but the explanation and logic behind this takes too many words to put down without running the risk of people misinterpreting it and ramming everything in their paths ("Baraza said not to brake, so I didn't. What do you mean "How did I run over all those vegetable vendors in such an open space"?”). The best way to put it is not to brake unnecessarily.

b) Shed weight. Deny passengers and loads that are not essential to you, your mission or the well-being of the motor vehicle. Several pairs of high heels may sound like "essential" items to a Demio-driving fashionista, but they're critical to neither the hoarder nor the vehicle. Remove them from the rear seat footwells, along with bottles, tumblers, bedding, cookers, makeup and anything else you are toting around needlessly in the car.

c) Keep your windows up when driving at some speed (typically anything above 50km/h). Use the AC if it gets too warm in there, or crack open just one window, but only a smidgen, not all the way down, not even halfway. Yes, the AC increases fuel consumption, but you know what else increases fuel consumption? Drag. Open car windows create a lot of drag and the higher your speed, the greater the drag. That is why cars struggle to attain very high speeds and burn a lot of fuel to stay at those speeds.

There are several other ways to optimise consumption, but with those we'll be straying into hypermiling territory where you risk damage to your vehicle if you don't know what you are doing or you become a traffic hazard through dangerous and inconsiderate on-road behaviour. Let those ones be for now, it's never that serious

As a wrap-up: don't freewheel in neutral, aka "coasting" aka "dieseling" aka "kuweka free kwa mteremko". That's an obsolete hang-up from the days of old to extract gains that are as imaginary as the mechanical knowledge perpetuated by people who should have spent a bit more time in school. Do not drive in neutral.

I’m mulling over the Toyota Surf Station Wagon or Kluger, how do they compare?

Hi Baraza,

I have been a regular reader of your column for several years now. I however cannot recall you reviewing either the Toyota Surf Station Wagon or Kluger. I like their looks. Performance wise, how do they compare to the Prado? I am planning to acquire either one of them (petrol) anything from 2013 upwards.

LFM

Hi LFM,

The reason you may not recall any of these reviews is because you may have skipped one or two Wednesdays in the lineup - there have been 573 of them since I started this column. Last week but one (July 21) was the 11th anniversary of Car Clinic.

I distinctly recall writing about these vehicles, more than once, in fact, touting the Surf's similarity to the Prado due to them having common engines and a common platform, and the Kluger's position as the quiet man's Toyota Harrier.

Performance: well, as I said, the Surf is the Prado in a little black dress (the analogy applies to the bodywork or the scantiness thereof, not sex appeal, so please shelve the accusations of contradiction within the same correspondence). The performance of the two is exactly the same.

The Kluger may be faster or slower depending on which Prado you are comparing it to. These new age 1KD and 1GD-powered Prados seem to go like bats out of hell, while the 2.7 Prado has been accused of lethargy, a charge it is not quite able to defend itself against - not that it needs to. You don't buy a Prado to participate in the Dakar, and if you do, then it won't be in the same shape at the race as it was in the showroom. So the 2.7 being slow is not so much an arraignment as it is a description.

Between the Kluger and the Surf, either will do. Get the Surf if you wander off the beaten path with some frequency, get the Kluger if all your driving is limited to easy and/or existing roads, simply because you won't need a Surf then. A third criteria to be used when choosing is a non-professional one I apply myself: buy the cheaper one.

Why didn’t you talk about the Mitsubishi D5?

Hi Baraza,

I have gone through your article on minivans but didn’t understand why you didn't mention the Mitsubishi D5.

It is a great van, I own one, and you need to try it. Very spacious and better ground clearance. On average, consumption is 11km per liter (petrol 2000cc engine)
Eric

Hi Eric,

Well I didn't mention the D5 because it didn't spring immediately to mind, and with good reason. It may be a good van, but I wouldn't stretch as far as calling it "great". There is a reason you don't see many of them around, greatness or no greatness, and that is because despite the alleged greatness, the vehicle is still outshone by the competition in several key areas, most of which I covered in that article.

I have not tried one professionally, but I have ridden in one and I didn't find anything particularly outstanding. 11km/l from a 2.0-liter van is not half bad, but it is still not exceptional, it is more like the norm. You can even attain that figure in a V6 -Alphard if you have driving skills like mine.

The D5 comes in second after the Serena with a vehicle length of 4730mm (the Serena is 4770mm long), but the 2019 facelift edges ahead with 4800mm. I don't think you were referring to the 2019 car, were you?

The price is not friendly either. With my million-shilling first generation Alphard as the baseline, all the vans we compared last time varied in price from Sh1.3 million to about Sh1.6 million. The D5s I found online start at Sh1.7 million and creep ominously close to the Sh2 million mark. This is the first complete defeat the D5 faces against the other 2014 vans and my old Alphard.

The other criteria are fairly subjective, but I doubt the Delica can keep up with my Alphard if the truth is spoken. You cannot beat an Alphard on long trips, you just can't, unless you resort to unaffordable options like a tricked out Mercedes Sprinter RV, or the V Class Viano. The same applies to legroom, luggage space and comfort, and as far as maintenance goes, the less said about Mitsubishis, the better.

However! There is one thing you mention that I'm pretty sure is the actual reason you own a D5 and is also the reason you call it a "great van": ground clearance. The D5 has clearance for days and has in previous generations been used as a platform for the crowd that goes off-roading in vans. It is surprisingly adaptable to modification, and with minimum effort and investment, can be converted into an excellent overlanding rig. The D5 looks ready for this transformation too, more so if you avoid city-dwelling spec levels like the Roadest.

So, perhaps the D5 is a great van after all, but this will only apply and appeal to a specific demographic: overlanders. As far as regular people-carrying goes, the Alphard still rules the roost.

Which Subaru Forester generation does not have the head gasket problem?

Hello Baraza,

Thank you for the enlightenment on cars, much appreciated. Remember the story of the Mark II that would hesitate to start in the morning? After systematic elimination guess what? It was the valve stem seals that were worn out, allowing oil seepage onto the pistons and fouling the spark plugs overnight or when the car was stationary for four hours plus.

This was missed because the car did not have the classical signs of worn valve stem seals. The car is now back to its usual self despite its advanced age.

Talking of the Subaru Forester, which generation does not have the head gasket problem, which is the best model to acquire and how does the 2014 Forester compare to the same year Honda CR-V and Mazda CX-5?
Douglas

Hi Douglas,

Good stuff on the Mark II. I hope it stays in good form. Now, the Subaru Forester vis-a-vis gasket issues. Well, they use the same family of engines as all other four-cylinder Subarus, and the problem was endemic to the EJ series. So any EJ Forester would be prone to gasket issues. To avoid this problem, that means you have to sidestep anything made before 2012 when the SJ generation introduced the FA and FB family of engines.

There is a small problem here: the FA/FBs have not been around or abused and mishandled long enough to determine their susceptibility to gasket failures, but they are direct injection engines and they have already started showing the weak points of that technology: carbon buildup.

It seems like there is no escaping one obstacle or the other, but take heart. Carbon accumulation is easier to deal with than fried gaskets - to get rid of carbon, you either need to use these special fuels (V Power, Excellium et al) or do an Italian tune-up: rev the engine as close to the red line as you can for some time, at least once a month.

Some of us do this while in motion just to make the maintenance exercise a bit more fun, but I'm not advising you to do this. I'd advise you combine the two methods: fill up with V Power (preferably, because the higher octane rating prevents knock) AND do the Italian tune up while running that V Power.

I have compared the Forester to the CRV and CX5 several times before, and the Forester won every single time.

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