Why does the Toyota Prius get much better MPG then the Lexus CT 200h?

[Kitdy]

16% is a fairly sizeable improvement.

The difference in between the two coefficients of drag is 0.04. 0.04/0.25=0.16.

Yay, math!

For Northern North America (once again, Canada is forgotten) there are no diesel Fiestas available here, and the only diesel Golf is the TDI with the 2L.

[Ferrer]

Since the topic has been more or less changed, I frankly don't understand why the eco mods aren't offered, at least as an option, on all models.

[pimento]

Exclusivity = moar profits.

[FastDriver]

yay! I got mail! Yay111~!~

[culver]

So the Toyota Prius and Lexus CT 200h both have the same drivetrain.

The drag coefficient on the Prius is 0.25
The drag coefficient on the CT 200h is 0.29

The weight of the Prius is 3042 lbs.
The weight of the CT 200h is 3130 lbs.

Yet Gas Mileage Varies Big Time

The Prius gets 51 in the city and 48 on the highway
The CT 200h gets 43 in the city and 40 on the highway

Can anyone please explain the huge difference in Fuel Economy?

I wouldn't trust the Toyota published CoD for the Prius. According to Toyota it doesn't change when fitted with larger OEM tires. That seems unlikely. Also, when GM tested the car compared to the Volt in their own wind tunnel they were not able to reproduce Toyota's numbers.
Chevy Volts Coefficient of Drag is 0.28, Beats Prius and Insight

Aside, your signature lines seem dangerously close to spam to me.

[Lukeno52]

Then again, conversely, GM will want to make the Prius sound worse, so you can't trust them either. Most drag figures, like other figures, are massaged by the manufacturers.

[henk4]

in the European cycle the Prius gets 3.9 liter per 100 km on average, the CT200h 3.8 so it is a slightly more economical.

[Ferrer]

The Auris Hybrid also gets slightly better figures than the Prius, but in real life tests the Prius beats it.

[henk4]

The Auris Hybrid also gets slightly better figures than the Prius, but in real life tests the Prius beats it.

By how much?

[Ferrer]

Half a litre, IIRC.

I'll try to find the tests if you are interested, but they'll be in Spanish.

[culver]

Then again, conversely, GM will want to make the Prius sound worse, so you can't trust them either. Most drag figures, like other figures, are massaged by the manufacturers.

Not likely. GM has been pretty reliable about these sort of numbers over the years. A few years back when the SAE tightened up the hp testing standards to close some of the loop holes GM had a few engines that actually gained rated power while Toyota's motors almost all lost rated power (no change in actual power). Also, Ford and Chrysler both agree with GM's numbers. It's quite possible that Toyota got those numbers using a best case test that is reproducible but perhaps only represents a best case condition. Also, Toyota does one thing that really suggests they aren't being 100% honest with their numbers. A change in tire width will almost always affect aero numbers. Toyota claims no change in numbers between any version of the Prius despite different wheels. The difference in the wheels is significant enough that one would expect to see a change in the CoD numbers. GM, did do one thing that is perhaps dishonest, they say they test cars with similar equipment. That means buy default they tested the Prius with the large wheels since those wheels are the same size as the Volt wheels. If they tested the lowest drag wheels perhaps the Volt and Prius numbers would be the same. BTW, it also seems unlikely that the Volt, being so close in shape to the Prius, would have a much higher drag number (the claimed .28 vs Toyota's claimed .25).

[henk4]

Half a litre, IIRC.

I'll try to find the tests if you are interested, but they'll be in Spanish.

well, I would say that difference would be within the range of circumstantial differences, like both cars tested at the same time on the same place with the same driver....

Apparently the US-EPA figures differ by about 20% while the ECE figures or spot on the same. Perhaps we are getting different versions of both cars here?

[Ferrer]

well, I would say that difference would be within the range of circumstantial differences, like both cars tested at the same time on the same place with the same driver....

AFAIK, same driver and same roads, but different times. However he is quite anal about conditions, apparently.

If anyone's interested there they are (I'll include the Auris Diesel and petrol):

Prueba de consumo (32): Toyota Prius III (híbrido) | Curvas enlazadas
Prueba de consumo (35): Toyota Auris HSD (híbrido) | Curvas enlazadas
Prueba de consumo (43): Toyota Auris 1.6 Valvematic 132 CV | Curvas enlazadas
Prueba de consumo (50): Toyota Auris 2.0 D-4D 126 CV | Curvas enlazadas

Apparently the US-EPA figures differ by about 20% while the ECE figures or spot on the same. Perhaps we are getting different versions of both cars here?

At most different settings, but the cars are probably mostly the same. I don't think Toyota wants to lose economies of scale by offering completely different cars, cars which in some markets won't see very important sales.

[henk4]

very interesting, so the differences are really small. Apparently their big deception is the diesel, but they drove that with a slightly higher average espeed than all the other versions.....and it might also be the case that Toyota puts relatively little effort in producing real frugal diesels, as that type of engine is not their marketing spearhead.

[drakkie]

If you are interested, my school has a CT200H running some cycles on the dynometer this and next month. I'll try and get the results of that.