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In the latest R&T there is a comparison of the BMW 328 and the MB C250. The 1/4 mile time for the BMW is 13.9 seconds. It weighs 3560 pounds, has 240 hp, 255 lb tq and an 8 speed autotransmission. I'm amazed with the 1/4 mile speed considering the weight of the car. 20 years ago, the 3rd gen RX7 weighed 2830, had 255 hp, 217 lb tq and a 5 speed manual transmission. It also had a 1/4 mile time of 13.9 seconds. The BMW weighs 700 lbs more and equals the Mazda in acceleration to the 1/4 mile. Does the BMW's 40 lbs of torque make up for the difference in weight or is it the transmission?
 

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In the latest R&T there is a comparison of the BMW 328 and the MB C250. The 1/4 mile time for the BMW is 13.9 seconds. It weighs 3560 pounds, has 240 hp, 255 lb tq and an 8 speed autotransmission. I'm amazed with the 1/4 mile speed considering the weight of the car. 20 years ago, the 3rd gen RX7 weighed 2830, had 255 hp, 217 lb tq and a 5 speed manual transmission. It also had a 1/4 mile time of 13.9 seconds. The BMW weighs 700 lbs more and equals the Mazda in acceleration to the 1/4 mile. Does the BMW's 40 lbs of torque make up for the difference in weight or is it the transmission?
Transmission makes the biggest difference as ultimately it is horsepower "under the curve" per weight that is what makes a car accelerate.

The rx7 has a very peaky powerband and with larger spacing between the gears the average power under the curve is likely considerably lower than the BMW which has a wider powerband and much less spacing between gears. So the BMW may have an average of around 230 something under the curve while thr rx7 is likely closer the the 210ish range.

Additionally there are lots of other small factors that add up to better acceleration such as faster shifting transmission, traction, different rating standards, etc.

Not as cut and dry as looking at simply a peak horsepower number against curb weight.
 
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