Fuel mileage

pontiac
lemans

#1

I had a '63 Pontiac Lemans Tempest with a transaxle hooked to a slant four that got 52 miles to the gallon. In this day of increased demand for better mileage, why is it so hard for the automakers to get over 30 mpg?


#2

Maybe if they installed less acurate odometers we could achieve the same MPG.


#3

there are still new cars around that get 40mpg or so. If you took one of these and stripped out all the safety features and the anti-polution controls, the AC, automatic transmission, etc, and drive it very carefully, it probably would get over 50mph also.

The laws of physics have not changed in the last 40 years.


#4

No way did a '63 Pontiac Lemans Tempest get 52 mpg! Probably not even half that value.

And what’s this about a transaxle in a 1963 American car? Got any photos?


#5

thought that transaxle bit sounded funny…


#6

While the part about the 52 mpg is clearly unmitigated bulls***, the part about the transaxle is actually factual.

The Tempest was one of GM’s “second generation” compacts, after the Corvair was introduced, and there were minor differences between the Pontiac Tempest, the Olds F-85, and the Buick Skylark variations. The Pontiac version had a slant four that was created by, literally, casting just half of a Pontiac V-8. It had the advantage of having parts that were interchangeable with the V-8. However, it had a really nasty trait of a slack timing chain by, at most 50k. And, while it was not an interference engine, there were lots of stranded Tempest owners once those timing chains jumped gears or snapped. Not a good design.

The other unique features of the Tempest included a transaxle in the rear (it was a rear-drive car, naturally), and the power was transmitted to that transaxle by a flexible drive shaft that was kept in a slight downward depression (sort of a “sagging” alignment of the driveshaft) underneath the passenger compartment. Of course, that flexible drive shaft turned at the same rate as the engine, so at highway speeds that shaft was turning at about 4,000 rpms or maybe more–and it always felt like that inside the car, unfortunately. Not a good design.

The transaxle was a 2-speed automatic transmission (as was GM’s practice at that time on their cheapest cars) and it had only inboard CV joints, thus leading to REALLY bad camber problems when the car had passengers in the rear. After a couple of years, many of the Tempests had a permanent bad camber problem, even when they were not loaded, thus leading to handling that was…interesting…to say the least. And, the rear tires were usually shot on the inner edges after 10k unless they were rotated very frequently. Definitely not a good design.

If anyone thinks that the '60s were the “Golden Era” of GM engineering, the Pontiac Tempest is Exhibit A in my rebuttal of that argument.


#7

Thanks VDC for this fascinating piece of automotive history.


#8

52 MPH sounds a bit high, but I had a Ford Granada that got over 30MPH on the highway at one time just by tuning everything constantly to perfection several times a week. I was constantly working with that carburetor.

We’re also getting cars with a lot less torque and horsepower, too. But, the exchange is we are driving cleaner cars. That is probably why gas mileage is different, because of all the smog controls. But, on the other hand, our fuel and ignition systems have gotten much more efficient.

So, I don’t know why it’s hard for them to get higher mileage cars.


#9

Actually, we are experiencing a horsepower (and torque) “war” with an unprecedented combination of power, fuel economy, reliability, driveability, and low emissions.

They don’t build 'em like they used to, and that’s a beautiful thing!


#10

I seriously doubt if many Tempest every got a true 52 mpg. They just did not try that hard back then for mileage when fuel was 17? a gallon. I was driving back then and nobody was getting 52mpg other than those who stripped the car, changed out the gearing, and modified the engine.

BTW I do get upper 40’s in the city and upper 50’s - low 60’s on the highway with my small diesel.


#11

Yup, if I was looking for a good mileage car today I would be definitely be shopping for a used TDI.


#12

Might have been 52 kilometers per imperial gallon…


#13

“If anyone thinks that the '60s were the “Golden Era” of GM engineering, the Pontiac Tempest is Exhibit A in my rebuttal of that argument”.

At least GM was innovative in the early 1960’s with the Corvair with its rear engine, the Pontiac Tempest with the front mounted engine and rear transaxle, the Buick Special and Oldsmobile F-85 with the aluminum V-8 followed by the Buick V-6. By 1964, the Pontiac Tempest, Oldsmobile F-85 and Buick Special became more conventional cars, and to me, less interesting. The Pontiac did adapt one of the GM six cylinder engines to an overhead camshaft engine for the 1964 or 1965 models. I think some the engineering in the 1970’s was worse with the Chevrolet Vega and later the Oldsmobile V-8 engine that was converted to a diesel.


#14

All these GM innovation had the common fault of poor detail execution and refinement; in other words, a half heated effort to innovate without the commitment to improve. The Vega was probably the worst example.

However, when they sawed 2 cyliners off the Buick V8 and created the famous 3.8 engine, initially it was rough running because the firing order and crankshaft throws were unchanged. Then they gardually refined it because it had to become the mainstay engine for their familiy cars. It turned out to be one of the best engines in the industry, although not the most advanced.


#15

Yes, GM was innovative, but unfortunately in the '60s (and especially during the '70s, and possibly into the early '80s), GM used the driving public to test concepts that were not fully developed or properly tested by the corporation. Innovation is fine, but without complete development and testing, GM wound up alienating a lot of customers who resented being sold vehicles that just hadn’t been perfected prior to sale.

To the Tempest, we can add (as you mentioned), the Vega and the Olds Diesel, plus the Chevette, the Cadillac V-8-6-4, the 2-seater/mid-engine Pontiac (can’t recall the name) and gems such as the smaller models that required the engine to be hoisted in order to replace the rear spark plugs (those same cars also had pitifully undersized brakes that wore out by about 15k). And, of course, let’s not forget the full-sized Chevies that were fitted with a Chevette automatic transmission that could not withstand the torque of the larger engines.

I firmly believe that GM’s engineering is currently far superior to what they foisted on the public for many years.


#16

In my neck of the woods, gas ranged from about 24.9 cents to about 28.9 cents during the early '60s. But, as you said, few people were really concerned about fuel economy in those days, and as a result, the US car companies did little to develop truly economical cars.

And, as we already know, that '63 Tempest was probably capable of, at best, 30 mpg–with a tailwind and on a downgrade. ;-))


#17

Interesting post. Actually, “swing axle” rear ends were common in the '50s and '60s for cars with independent rear suspension. Have you ever been behind a Triumph Spitfire?

My '61 Beetle, my first car, had swing axles…if memory serves.

GM made some disasterous mistakes in the '60s, but they also made some of the best iron in the world for working class folks. Right up until about 1970. And we won’t even mention my 1972 Vega that I bought brand new…the model that the rear wheels often fell off of!


#18

“The Pontiac did adapt one of the GM six cylinder engines to an overhead camshaft engine for the 1964 or 1965 models.”

My cousin bought one of the OHC 6s. He was very proud of it.


#19

My 4cyl civic has just over 70 less horses(195 vs 127) and a third of the torque(300 vs 107) my v8 Chevelle had. there are 4cyl engine pumping out more horses than my chevelle had


#20

You hit the nail on the head. GM didn’t finish developing some of its ideas before springing the cars on the public. I owned a 1961 Corvair and it was a good example of what you are saying. I put a transverse spring between the swing axles to limit the camber, and it really improved the handling. I think I paid $12 for this item. GM could have installed it from the very beginning of the marketing of the Corvair. The second generation Corvair which came out in 1965, was, in my opinion, a very good handling car for the time. I’ve always felt that had GM really developed these innovations before releasing them, cars would be a lot different today and GM would still be a leader. This left a gap for the other manufactureres to use a “tried and true” but antiquated design to sell their products. The Ford Falcon was certainly not as innovative as the Corvair, but had fewer problems. The two seater mid-engine Pontiac, called the Fiero, could have been an exciting car, but was released before it had been thoroughly tested.
GM was capable of bringing innovative new models to the market that did work well. The advanced design Chevrolet and GMC pick-up trucks released in 1947 were far superior to the earlier models and held up well. The entire 1949 automobile line of GM was a break from its past vehicles and performed well for the time. The 1955 Chevrolet was completely different than earlier Chevrolets and had a good reputation for reliability. I think much of the trouble at GM happened when the accountants started dictating company policy.