it’s bullshit. automatics took over because most people don’t want the hassle of a manual transmission. even back when you were choosing between a 3-speed non-OD slushbox and a 5-speed OD manual- where the manual could have 8-10 mpg better fuel economy- a lot of people were still going for the auto.
now that automatic transmissions have as many or more forward gears than manuals, there is no reason whatsoever to take a manual transmission unless you specifically want one.
This. The only reason a manual would deliver worse fuel economy than an auto would be if top gear were lower (putting the engine at a low-load, high-rpm condition during cruise), or if the shift points specified in the owner’s manual (and used during fuel economy testing) were higher than they really needed to be.
I’d ask why the scooter ONLY gets 129 mpg.
The Honda Fit (Jazz) compact car gets 32 mpg. It weighs 1130 kg, so let’s say 1200 kg including driver.
The Honda Activa scooter weighs 110 kg, so it’s 180 kg with the same driver. That’s 6.7 times less, so if tire performance were the same, the rolling resistance would be 6.7 times smaller.
The frontal area of a scooter depends largely on the rider, but I’d WAG it as width x height of the scooter + 50%, which would be about 1.1 square meters. Honda Fit width x height is about 2.6 square meters. But air resistance scales as square of speed. If we guess average speed for each to be 30mph and 50 mph, the scooter should get (2.6/1.1)*(42/25)^2=6.7 times smaller air resistance.
Which means the Activa scooter should get 6.7x better gas mileage than the Fit, or 215 mpg.
Cost is the answer. The activa is not the most efficient scooter on the market it’s just a common one in Asia which is why I picked it. They sell the Activa for 50000 Indian Rupees in India or $785 USD new. At that price they can’t afford to put all the fancy fuel saving tech that the Fit uses onto it.
And there probably isn’t a market for a super fuel efficient scooter, as anyone that would pay that much would probably by a small car instead. The $780 price point meets a “good enough” standard of fuel efficiency and is cheap enough for the market in India.
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fueleconomy.gov says the 1989 Honda CRX HF got 37 city 47 highway/ I got 38 driving back and forth to work (8 miles each way) and topped 80mpg on a 1200 mile road trip, and that car was 10 years old when I got it. My Mom got similar results from that car when she owned it… Well, I had assumed I had made a math error, but my stepfather said he got similar mileage on a similar trip he made each summer in that car. I was often reaching 80-85mph, and as I said the trip was 1200 miles. I would have been impressed with 50mpg.
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I was with you until you said 80-85 mph.
I used to have an 88 Honda Civic Wagon (4WD) which I used for several trips back and forth from East Tennessee to Northern Illinois, and I noticed that the fuel economy varied dramatically with my cruising speed. Traveling at 65 mph I got 28-29 mpg (the EPA highway rating for that car was 27). But when I decided to slow down to 55 mph and keep it there (even though the speed limit was 65 and cars were passing me constantly) my fuel economy improved to 37-38 mpg on the exact same trip. I repeated this experiment 3 times, with the same results.
I find it plausible that you could take a car which gets 47 mpg at 65 mph and get 66 mpg by slowing down to 55 mph. I might even believe 80 mpg, if you slowed down to 50 mph. But you claim you were hitting speeds of 80-85 mph. That’s where you lost me. Sorry, I don’t buy it.
It’s worth noting that engineering students have built vehicles which use off-the-shelf Briggs and Stratton 5 HP lawnmower engines and get 1,000+ miles per gallon. But they do it by making the vehicle extremely lightweight, extremely low profile, high pressure narrow tires, no air conditioning, and keeping their speed down to something like 20 mph.
Now, if you modified you Honda CRX-HF by removing the windshield wipers and the side mirrors, covering up most of the radiator grill, taping over the door handles, everything you could possibly do to reduce wind resistance, and put high pressure low rolling resistance tires on it, and kept your speed down to 55 mph then I’d believe you could get 80 mpg out of it.
If the per-mile energy requirement is 6.7x smaller, then the only remaining issue is the efficiency with which the energy is taken from the fuel and delivered to the drive wheel. And that’s where the scooter falls short.
The scooter+rider has a smaller frontal area and lower speed, but compared to the Fit, its shape is awful. Give the scooter a fully enclosed fairing with a long sloped nose and something like a Kammback tail, and it starts to resemble the Fit (in shape, not size); the fuel economy would improve substantially.
The scooter’s belt-drive CVT also isn’t very efficient. If you replaced that with a manual transmission that had real toothed gears in it, you’d probably get another jump in MPG.
Finally, there’s the engine itself. The scooter engine is carbureted (so questionable fuel mixing), fixed spark timing (can’t advance it for best efficiency at elevated speeds/loads), probably runs a little rich to keep temps down (so raw hydrocarbons and useful energy are being dumped out the exhaust), probably has low compression ratio to cope with air cooling (limits max theoretical thermal efficiency), and the tiny combustion chamber has much higher surface-area-to-volume ratio (greater proportion of heat lost to the head/cylinder instead of going to mechanical work during expansion stroke).
So relative to the Fit, the scooter is not as good at converting the chemical energy of the fuel into mechanical work at the drive wheel - but it still gets far better fuel economy by virtue of having a low per-mile energy requirement to begin with.
He lost me with a '75 400CI Chrysler that got 26MPG delivering pizza.
NOT. GOING. TO. HAPPEN.
Well, my Honda 125 CGL, which has very old technology regularly gave me 75mpg so I can see that a modern, CVT scooter can do well over 100.
I want to be clear here: that 80 mpg was a one-time thing, and as I said I thought at the time I had made a math error. I only gave it credit because my stepfather had said he’d done the same with that car.
However, about speed: the gearing on that car was mighty weird. You could shift into 3rd below 30mph, and it was fine up to nearly 60. 5th gear was useless except on the open highway; at 55mph in 5th it would lug and acceleration was nearly impossible. So part of what I liked about that road trip was the promise of getting to use 6th gear some.
I could either shift into 5th at about 65 and then slowly inch up my speed, or I could just stay in 4th until I was doing 80, then shift into 5th and back off the gas.
There was a light on the dashboard to tell you when to shift. My mother reported that light broke within a week of buying the car new, and after 3 attempts to get it fixed at the dealership she just gave up.
I am totally willing to believe that I screwed up the math, and that I was really getting 40mph. As I said, the only reason I didn’t recheck all my math immediately was that when I commented “I must have screwed up the math somewhere, because I think I got 80mpg.”, my stepfather replied “That’s about what I’d get when I drive it to Michigan.”
Part of the problem was that the gas gauge was broken, so I was stopping for gas every 300 miles or so regardless. I was just buying surprisingly little gas at those stops. (it was a decade ago, I have no idea how much gas I bought on that trip.)
I have a modern CVT scooter with a carbonated 49cc engine, and I get about 108.
I do almost all my driving near the redline, and when I had a tire with a slow leak (so it was a little soft some of the time), mileage dropped to the mid 90s.
carbeurated, not “carbonated” Curse autocorrect!
Fifth, not Sixth. Only 5 gears in that car.
I have a 2008 Yaris, 2009 Ranger and 2013 Elantra GT. On the Yaris and Ranger, the manual was rated higher (only 1 mpg, but that’s higher!) and on the Elantra, it was the same. Resale? I always keep my vehicles until they have hit rock bottom, as far as resale goes. Of the last four cars I went through, two were totaled and two others I gave away. Your resale argument doesn’t apply to me.