Emission controls in early 70's (MPG, truck, mileage, engines)

[rlrl]

Check out these mpg figures tested by CR's on these 72 and 73 Gran Torinos:

72 Gran Torino with a 250 inch 6: 11-21 mpg in normal driving; 18 mpg on a 300 mile trip

73 Gran Torino with a 302 inch V8: 8-15 mpg in normal driving; 14 mpg on a 300 mile trip

would you say the difference is caused by engine size or by emission controls?

and btw that 8-15 range in normal driving is horrible even for a mid sized car. several big cars with much larger engines have managed more than just 15 mpg in the upper range that year

[mshultz]

Some of the difference was caused by the way Consumer Reports drove the cars. I remember when they tested 6 cylinder cars along with a V8 (they were unable to find that model with a 6). They complained that the V8 would have gotten worse mileage if they had been able to test it with a group of V8 cars. In other words, they drove cars in a way to reinforce their biases. The drop in compression ratio in 1971 to allow the use of low-lead gas really affected engine efficiency. Also, emission standards became much stricter from 1972 to 1973, resulting in even greater efficiency losses.

[rlrl]

when did low lead gas begin? i think our 1975 Buick Century took no lead gas. was it 1975?

[rlrl]

was that report in 1974 where they tested the Chevelle, Satellite and Matador with 6's but the Gran Torino had the V8?

[M3 Mitch]

1973 was not a vintage year for Detroit, and '74 was worse. The crude emissions controls of the day frequently included retarding the spark when not in high gear, way low compression with a cam with little lift but lot's of overlap to make a crude EGR system, and don't forget the heavy ugly 5-mph bumpers. A '72 or earlier car is a way better car in terms of power and MPG compared to the bad old days of 73-74. The first cars to *require* unleaded gas are 1975 MY. These were the first cars with cats, and the beginning of the performance renaissance that continues to the present day.

[rlrl]

i remember that year in 73 some cars got dreadful mpg's (Chev Nova with 250 6 got 10-18 mpg in normal driving and 14 mpg on a 300 mile trip which is terrible for an economy car) and the Pontiac Grand Prix with the 455 V8 actually got the highest mpg on a trip (16 mpg) for that year

the loser of that year was the Olds Omega with 350 V8 4 bbl carb--11 mpg on a 300 mile trip. thats pitiful for a compact even with a V8

[M3 Mitch]

I took driver's ed in 1973 MY new GM cars. Long story short - they sucked. Probably this is when I became a hard-core old car guy. Slightly off topic but I once dated a gal who had an 84 Ford Escort, 4-pot, automatic. It always amazed me how bad the MPG on this car was - it might get 25 MPG - with it being so small and so slow. I'm getting MPG numbers like you quote, rl, with a 1978 Ford F-350 hauling fire wood a cord at a time. Not driving that truck like I stole it, but at least it's doing some work to justify it's appetite.

[rlrl]

mitch youre 5 years older than me as i took driver ed in 1978. first car i drove was a 77 or 78 Bonneville. super smooth and slick

[M3 Mitch]

Yeah, after '75 things got a bit better. Although it was sometime in the '80s when the real power started coming back.I forgot that there was one car in 73 that didn't suck - the Trans Am. I don't know how they managed, but it was decently fast, not up to late '60's standards, but not as awful as most of the other junk for 73.

[thunderkat59]

Yeah, mid 70's for the USA was not our finest moment. Big, rubber bumpers, positively wheezy motors . . . I was a kid really into cars in the 60's, 70' and 80's and watching the progression through the 70's was painful. The Chevelle and Nova for instance, the drastic change GM took with those body styles was sad. Mustangs were that little Pinto based debacle, the Duster morphed into that Volare thing ~ Cordobas, etc oo0OooF
Thank goodness for the Gremlin X