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Mazda MAZDA3, Volkswagen Rabbit, Car Comparisons, Hatchback
#370 of 389 Re: Beautiful = over 30 and under 3000 pounds [backy]
Oct 18, 2008 (6:53 am)
Are you comparing your actual mileage with EPA figures? If so, that is not a good way to do a comparison. You can compare EPA figues, CR figures, or your own figures, but mixing and matching is meaningless. Your BMW may be rated something like 18/26 by EPA (and uses premium).
While your BMW is a 6 cyl, isn't it just a 2.5? If so the HP and displacement is not much different from many 4 cylinders today (or VW's 5 cyl).
In particular, here we are talking about the 2.5L 170 HP VW 5cyl and a car that weighs about 3100 pounds in the case of the Rabbit. The Mazda3 2.3 uses the same 2.3 engine that last year's Mazda6 used, though weight is a couple hundred pounds less than the 6 was.
#371 of 389 Re: Beautiful = over 30 and under 3000 pounds [jeffyscott]
Oct 18, 2008 (9:04 am)
The BMW is a 2.8L, and the FE numbers were from real world experience, as were the numbers discussed earlier in this thread for the Mazda3 and Rabbit.
The number for the mid-sized car I mentioned, a 2009 Sonata, were EPA, since I don't have my own real-world numbers on that car. They are 22 city, 32 highway--better than the much smaller Mazda3 and Rabbit even though the Sonata is heavier and more powerful. Other mid-sized cars, e.g. the Malibu and Accord, also get better EPA FE than these two small cars.
Anyway, that's not the topic here, but I thought I'd mention some other data in support of the earlier post that these two small cars should get better fuel economy.
#372 of 389 Re: Beautiful = over 30 and under 3000 pounds [backy]
Oct 18, 2008 (8:28 pm)
So I am wondering, why can a 3200 pound BMW with a 193 hp I6 and a stick shift get mid-30s on the highway and mid-20s in town, while these newer, lighter cars with much smaller engines can't make those numbers?
A lot depends on the power / torque curve and transmission gearing. Mazda and Volkswagen engines tend to be torquey and have great low end power. That kills city fuel economy. I know Mazda's are geared very high, even in top gear, which hinders highway FE. I'm not sure about VW's.
Why do you think Honda 4 bangers do so well in FE tests? They have no torque, and the their power band is near the top of the RPM range (that's VTEC for you). They are also have a low top gear. They are built to excel in EPA tests, however, when you get on them, like in performance tests, they usually get beat in the FE category because they are driven to get all the power they can out of them just to keep up with the others in those tests.
I've never seen the 2.8L I6 power / torque curve from the BMW, but I'm almost certain that there is not much low end power. Their gearing is also low in top gear.
#373 of 389 Re: Beautiful = over 30 and under 3000 pounds [aviboy97]
Oct 19, 2008 (12:27 am)
The BMW 2.8L was evolved from the 2.5L since 1996 w/ nearly the same peak hp but more low end & mpg, even by EPA!
EPA like to shift manual transmission at certain mph's regardless of gearing. So if you are smart enough, then you will shift as early as possible w/o lugging the engine. That way, you do get better mpg w/ fat-torque engines. Because, under the same output level, engines w/ low-end bias setting involve less total travel friction b/t the piston ring & the cylinder sidewall.
Engines are most efficient when there is about 0.5 liter per cylinder. Balance shafts also waste fuel. So don't get the 4-cyl Mazda w/ more than 2.0 if you want "the best fuel economy", which was exactly what CR said about the 2.0 Mazda3!
#374 of 389 Re: Beautiful = over 30 and under 3000 pounds [aviboy97]
Oct 19, 2008 (7:58 am)
I've never seen the 2.8L I6 power / torque curve from the BMW, but I'm almost certain that there is not much low end power.
FYI the numbers for the 2000 328 are 193 hp and 206 lb.-ft. at 3500 rpm. That seems like pretty decent low end power to me, by the numbers and from driving experience. That compares to 156 hp and 150 lb.-ft. at 4500 rpm for the 2.3L engine in the Mazda3, and 150 hp (170 for 2008+) and 170 lb.-ft. at 3750 (177 4250 for 2008+) rpm for the Rabbit. So I'd say the Rabbit has excellent torque for its size, but the Mazda3 is OK but not great there. Not great enough to excuse the relatively low fuel economy, IMO.
Also, I think you meant the Mazda3 is geared very low and the 328 geared high, not the converse, right? I am assuming you were trying to say that the rpms of the Mazda3 are relatively high at higher speeds and those of the 328 are relatively low. Actually, the top-end gearing on the 328 is pretty low, and the engine spins at higher revs than, for example, my 2.0L Elantra, and any other car with an engine of similar size that I have driven.
#375 of 389 Re: Beautiful = over 30 and under 3000 pounds [backy]
Oct 20, 2008 (7:41 am)
Mazda's, as well as other makes, usually far exceed their EPA estimates. Why, I have no idea. Most 2.0L Mazda3 owners report mid to high 30's on the highway, and usually an average of 30mpg. The 2.3L owners tend to get 32-33 highway, and mid 20's in town. Both real world MPG's are in excess of the EPA estimates.
"Not great enough to excuse the relatively low fuel economy, IMO."
Maybe so, but, that seems to be the truth. Is there more to it? Probably. Lack of technology could be it too. The new 2.5L seems to be much much better with owners reporting 30+ on the highway with ease.
#376 of 389 Re: Beautiful = over 30 and under 3000 pounds [aviboy97]
Oct 20, 2008 (8:12 am)
Mazda's, as well as other makes, usually far exceed their EPA estimates.
When driven reasonably, yes, I agree. But I know, and you also know if you've followed forums like the "real world fuel economy" discussions here at Edmunds.com, that it is possible and even common to not reach the EPA estimates. For example, I routinely exceed the EPA estimates on any car I drive, but my wife has the proverbial lead foot and doesn't hit the EPA numbers.
Which Mazda3 is the 2.5L engine available with?
#377 of 389 Re: Beautiful = over 30 and under 3000 pounds [backy]
Oct 20, 2008 (8:20 am)
The 2.5L was in reference to the 09 Mazda6....I should have clarified....My first few highway trips in the 09 6 got 32mpg on the first, and 33.4 on the second. Doing 70 on both with the a/c on.
2010 Mazda3 will have the new and improved 2.0L with the rumored start-stop system and more power. It will also have the 170hp 2.5L.
#378 of 389 Re: I have had my 07 Rabbit since Dec 06 [creakid1]
Oct 20, 2008 (8:47 am)
I also doubt the clumsy heavy bulky '03 Accord w/ huge turning circle really rides smoother than the Rabbit.
Dunno about comparing the ride, but for a midsize car, the previous generation Accord has a tidy turning radius, at 36.9 ft, versus the compact Rabbit with 35.8 ft. Considering the class of car, I don't think the Accord's radius is "huge," unless you consider the compact Vee-Dub's radius as "huge" also.
Yeah, I know its an old post, but I read it and couldn't help myself.
#379 of 389 Re: I have had my 07 Rabbit since Dec 06 [thegraduate]
Oct 20, 2008 (4:55 pm)
Agree, they both got huge turning radius. The '03 Passat does have relatively small turning radius, by comparison.