Assalamu Aalaikum everyone!
So my last thread about hypermiling seemed to be a little bit biased because my experience was only with a 'new car'. Hence, my statement "a̶s̶ ̶a̶ ̶h̶y̶p̶e̶r̶m̶i̶l̶i̶e̶r̶ ̶y̶o̶u̶ ̶m̶u̶s̶t̶ ̶u̶n̶d̶e̶r̶s̶t̶a̶n̶d̶ ̶t̶h̶a̶t̶ ̶t̶h̶e̶r̶e̶ ̶i̶s̶n̶'̶t̶ ̶a̶l̶o̶t̶ ̶y̶o̶u̶ ̶c̶a̶n̶ ̶d̶o̶ ̶w̶i̶t̶h̶ ̶y̶o̶u̶r̶ ̶c̶a̶r̶ ̶t̶h̶a̶t̶ ̶w̶i̶l̶l̶ ̶s̶a̶v̶e̶ ̶f̶u̶e̶l̶" Doesn't stand true for most of the cars running on our roads.
Which means that there are a lot of things that you must do before trying hypermiling on an older vehicle.
This thread is my journey from 6 Kilometers/Liter to 20 Kilometers/Liter on a fairly used vehicle.
So the story begins by me selling Honda City 2009 (due to some financial reasons) and making an attempt to buy a car that I really loved for a long time: Mitsubishi Pajero Mini. I know what you guys must be thinking as soon as this name is mentioned, I heard every possible bad thing I could ever hear about a car whenever I mentioned its name. One being its extremely bad mileage. I had this perception in my mind that if I could get 25 Kilometers/Liter with a 1.3L car, why should it be any difficult to get 25 - 30 kilometers/liter on a 660cc car? And the reason why everyone says they get 8-10 Km/L is because they push the engine hard enough to the point where it doesn't want to go.
So long story short, I became owner of a Pajero Mini. It was 660cc, 20 valves, turbo plus inter-cooler version. Luckily enough I got the version that had a fuel economy display (which is biggest reason why I chose this over others).
I drove it from Lahore to Islamabad, and it did about 12 KPL at 60 Km/H. I couldn't drive it faster than 60 because the gearbox wouldn't let me, and I knew even if I did try going over 80, I won't even get 8.
Extremely disappointed me, scratching my head.. why does a 660cc such so much fuel?!?! I went to the book, read what turbocharger actually does, and found out that this mechanically driven turbo basically throws more air into the engine as the revolutions of the engine increase (based on the pressure of the exhaust), as soon as there is more air in the cylinder, it sucks more fuel in, and so it "should" increase the amount of fuel burnt (should is in quotation marks, I'll tell you why in a moment).
Next day, took it to the mechanic, I asked him please swap the engine with a naturally aspirated 16 valve engine. I had talked to many people by then about the mileage they were getting in their naturally aspirated Pajero Minis (or other 660cc engine imported cars) and a couple of them quoted something around 16 to 17.. which was MUCH better than what I was getting.
Got the engine replaced. Now I was driving 16 valve, no turbo, no intercooler.. and guess what? I was getting 6 KPL with "EXTREMEST" hypermiling techniques. I would shift to neutral (remember it was auto-transmission), I would go from 0 to 20 in about 3 minutes (literally).. and would get 6..
Although there was an issue with the transmission, it would shift gears at atleast 4000 RPMs which is totally against the laws of saving fuel.
I went to the mechanic.. this time we decided to change the spark plugs. Strangely enough this particular step increased the mileage from 6 to 10 kpl, but I was not even close to being 'happy' with the mileage. WHY OH WHY DOES THIS CAR DO 10KPL???
Did some more research, and a few pages were talking about faulty fuel injectors being a cause. I went back to the Pajero Mini guy and asked him to change the injectors for me. He said its of no use, you will HAVE To shift to CNG, I said no, how can a Mehran do better, which doesn't even have a fuel-injected engine, and this cannot do even 15? I mean my situation was that as soon as I saw a two digit mileage of my display (greater than 9 kpl) I would become really hopeful that something good is about to happen. So 15 KPL was by that time a dream come true for me.
We swapped the injectors, I drove from double road (rawalpindi) via the Islamabad Highway to Gulzar-e-Quaid.. This time, I got 23.6 Kilometers per liter on the display.
To date, I am getting 19.5 - 20 on the highway (at 80 KPL) and 20-23 KPL on local (at 60).
And then I took a sigh of relief, and got the other things in the car fixed.. and am driving it for a pretty long time, much happy with the mileage.
But, pickture abhi thori see baqqi hai..
I did some more research, and 'technically' a turbo charged engine should give 'better mileage' at lower revs than a naturally aspirated one because of a few things that we understand when we read turbos and turbo charged engines, that optimizes fuel combustion.
So hopefully, in a few days I'll be swapping this 16 valve n/a with a 16 valve turbo charged engine and am a little bit hopeful that it will do better. 
So if you have a 10 or 12 years old car, may be these tips would help you guys out there get a much better mileage (regardless of automatic or manual transmission). Remember I got the mileage I did with an automatic vehicle.
This is all I can think of for now. Please do come with your findings and let us all know how much you've saved.
Thanks for reading!
