Here is an ad from 1977 that claims the Mazda GLC can get 46 miles per gallon.
46 miles per gallon!!!
Not to make myself feel old or insult younger dopers but…
NO F***ING WAY!!!
I was 17 in ‘77 and no car got that kind of fuggin’ mileage!! I was there, fuggers!!!
So?
Did the standards change that much, or did @#$$%^#%^%?
?
Well, it had a 1 liter, 45 Horsepower engine…
It’s amazing what you can do just by making your car really small.
God, that video is nostalgic. The four tires for $99.99 is especially notable to me.
But yeah, cars with high MPG were known in the 70s (I was there too), they tended to be small cars no one wanted to buy.
I remember Toyota Starlets that got over 40 mpg as well. A lot of these cars I remember were hitting the market in response to the gas crisis of the 70s.
The 1977 Honda Civic got 54 mpg…
Wait, shouldn’t that be Ctarlet? 
And really slow. If new car buyers today were willing to tolerate the atrocious performance of 1970’s economy cars, we would be seeing a lot higher mileage figures than we do. Most entry-level economy cars in the US today are faster than the sports cars and luxobarges of the late-70’s. New car buyers supposedly like good gas mileage, but they apparently like performance more and so the carmakers have pretty consistently used technology to get more power out of the same amount of engine instead of the same amount of power out of less engine.
Although the MPG ratings were also ridiculously optimistic back then. The EPA revised them downwards to make them more realistic in 1984 and again in 2008, so comparing a contemporary window sticker to an old car ad is far from apples-to-apples. 1977 46 MPG is probably in the mid to high 30’s in the current scheme.
The older ones got better mileage. By the mid-70’s the VW couldn’t really compete as an economy car any more because they were being undercut in price by the Japanese imports, so they tried to make them more fun to drive. By '77 all that was left in the US market was the Super Beetle, which had a more robust suspension, was slightly bigger and came with a downright fast fuel-injected 1600 dual port engine.
Well, it is a Mazda after all! Zoom-Zoom But as others have said the reason it got such high mileage was the engine did everything but Zoom-Zoom. As also mentioned, today’s drivers are so unaware of how powerful today’s cars are. It is simply nothing short of amazing. A moderately priced sedan today can easily keep up with sports cars of the 70,'s and 80’s. I know of a couple of sedans and even a few crossovers that are faster than a early 80’s Ferrari 308. Take powerful engines, add all of the modern toys such as dual air, power everything, tv’s, sound systems and such and you have got a heavy car with lots of go power. For them to get as good of gas mileage as they manage is a miricale. Look at most of the hybrids, they run on bicycle sized tires, and look like they are made of paper next to an average car. Engines are only a part of good mileage, weight is the other part. I remember around 1985 (get off my damn lawn) being so impressed with the Honda CRX as it got something like 35-40 MPG. That is why I don’t get the hybrids, they cost a fortune, but don’t seem much more of a car than the CRX, so why bother? Just build some more CRX’s.
Right, the MPG rating in those cars are under ideal circumstances. So, yes, on a downgrade, with a tailwind, as a steady 50 mph, with a perfectly tuned engine, and a professional driver, they maybe hit 46MPG for a few minutes.
Surely I’m misunderstanding you. Are you saying that a modern, say, Ford Taurus could keep up with a '77 Smokey and the Bandit Trans Am?
A '77 Trans Am squeezed 200 HP out of a 400ci engine, which was the biggest engine you could get. The smallest engine on the current generation Taurus is a 288HP V6. The Firebird might be a little lighter than the Taurus, but not by much.
Now, if we were talking about a regular entry-level Firebird, the small block V8 model only put out 110 HP, which is less than a base model US-spec Fiesta!
And really light in weight. A 1974 VW Golf weighed 810kg, a 2012 VW Golf is 1350kg.
Cars were a lot lighter back in the 70’s than they are today.
Astounding. So if Smokey and the Bandit were remade, Burt Reynolds would be outrunning Jackie Gleason in a Ford Focus? 
I don’t get some of the hype about ‘high efficiency’ cars today either. Chevy Sprints and especially Geo Metros from the 1980’s got really high miles per gallon. There isn’t much mystery about how it was done. It wasn’t much car but neither are some of the new attempts. The thing that is most appalling to me is how incredibly INEFFICIENT the new SMART cars are at least for the ones in the American market. Sure, they beat the average sedan but not nearly enough to justify the tradeoffs. You would think that a toy sized car with the newest technology could get incredible mileage but no, they only manage MPG in the low 30’s to low 40’s depending on the driving conditions. That’s less than a 1980’s Geo Metro.
GreasyJack addressed that question, but to put a finer point on it, consider the Mustang. The 1977 Mustang offered a 5.0 liter V8 which could wheeze out 140 hp on a good day. The 2013 Mustang GT offers a 5.0 liter V8 which puts out 420 hp, with comparable fuel economy. In a much heavier car.
Also, the “economy cars” sold in the US are more powerful and larger than the fuel-efficient economy cars sold elsewhere. In the US you can’t buy something like the Volkswagen BlueMotion Polo which gets 60 mpg, probably because they judged that US consumers wouldn’t be interested in a car with “only” 80 horsepower.
Mandatory safety equipment can be pretty heavy. The Smart fortwo is a tiny, tiny car—106 inches long, compared to a 1989 Metro/Swift/Cultus, which was 151 inches long in hatchback form. But the Smart is also heavier—1800 lb compared to 1600 lb—and more powerful (really!)—70 hp compared to 49 hp. Fact is, Americans just aren’t willing to sacrifice that much for fuel economy, especially not when you can get a 50 mpg Prius without the enormous size tradeoff.
IIRC, the Smart car sold in the US is slightly larger and has a different engine. The diesel model available in Europe has a 0.8-liter turbo diesel, and is rated for 83 mpg, or 69 miles per US gallon.