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Quick acceleration and good fuel economy


dezso3
03-07-2010, 11:16 PM
Which cars on the market have relatively quick acceleration and good fuel economy? One would think that the two are mutually exclusive, but are they? Obviously, a powerful sports/luxury car is not going to achieve good fuel economy, and a hybrid is not going to get good acceleration. So what cars are there that are not only quick and fuel efficient, but are also fun to drive and reliable?

jrecken
03-07-2010, 11:35 PM
I think I will add a Buick Lacrosse CXS with the 3.6
It is pretty fast and will easily get 27.5 mpg.

akboss
03-08-2010, 09:02 AM
Which cars on the market have relatively quick acceleration and good fuel economy? One would think that the two are mutually exclusive, but are they? Obviously, a powerful sports/luxury car is not going to achieve good fuel economy, and a hybrid is not going to get good acceleration. So what cars are there that are not only quick and fuel efficient, but are also fun to drive and reliable?

To be blunt, yes they are mutually exclusive. When a manufacturer lists their EPA mileage, they are running the car in optimal circumstances in a series of stop-and-go situations and with a cold motor (city) and with a warm engine at a relatively steady speed (highway). If you accelerate hard from a stop in any car, your mileage will drop to half of what the specified rating is.

Regarding hybrids, you are quite mistaken on their acceleration potential. An electric motor is much more efficient than an internal combustion engine - you have 100% torque from 0 RPM, unlike a gas motor where you have to build the revs up to 2-3000. In a hybrid-assist situation, common in lower-cost hybrid commuter cars and sedans, the car will use the gas motor under heavy load and use the electric motor to assist, so you are getting pulled by 2 motors, not just 1.

You will get terrible mileage in any car if you accelerate hard, but it will be less terrible with a hybrid. Also, turbocharged four-cylinders are a good option, because when you need the extra kick the turbo forces more air/fuel into your engine (wham!) and when you back off, the turbo winds down and you are just cruising with a four-cylinder car. Volkswagen AG is famous for great turbos - in 2003, their 1.8T made 180 horsepower, 180 lb-ft of torque, and got 30 mpg on the highway. In models 2006+, the 2.0T was up to 200 horsepower with similar mileage and less emissions. Unfortunately used VW's are a reliability nightmare, so if you want a 'reliable' turbo, you could look to Subaru, perhaps a few sports models like the MazdaSpeed cars - the 2006+ MazdaSpeed3 is a great little car.

MagicRat
03-08-2010, 11:29 PM
In addition to the above post, simple physics is at work here. All other things being equal, a smaller, lighter car will deliver both better fuel economy and better fuel economy.
So look towards the smallest cars (or better yet, a mid-size motorcycle :)) for this combination.

dezso3
03-10-2010, 11:20 PM
How come they don't make Subaru's with a part-time 4WD or AWD option, instead of making them all with full-time AWD? It could easily improve their fuel economy as well as their acceleration if people only turned on the AWD when the roads are snowy/icy. For example, the Subaru Impreza has an EPA estimated 20 MPG in the city and 27 on the highway, whereas a Toyota Camry, which has the same size engine, but is only two-wheel drive (2WD), gets an estimated 22 MPG in the city and 32 on the highway. If Subaru made cars that had a part-time four wheel drive option, I would most certainly buy one. Also, if you go to this link, you will see a picture of a Jeep's SELEC-TRAC shifter, with it having different options between 2WD, full-time 4WD, part-time 4WD, and 4-LO. I'm just curious, what do all these denote? What is the difference between them? http://www.wjjeeps.com/st_shifter.jpg

akboss
03-11-2010, 08:47 AM
How come they don't make Subaru's with a part-time 4WD or AWD option, instead of making them all with full-time AWD? It could easily improve their fuel economy as well as their acceleration if people only turned on the AWD when the roads are snowy/icy. For example, the Subaru Impreza has an EPA estimated 20 MPG in the city and 27 on the highway, whereas a Toyota Camry, which has the same size engine, but is only two-wheel drive (2WD), gets an estimated 22 MPG in the city and 32 on the highway. If Subaru made cars that had a part-time four wheel drive option, I would most certainly buy one. Also, if you go to this link, you will see a picture of a Jeep's SELEC-TRAC shifter, with it having different options between 2WD, full-time 4WD, part-time 4WD, and 4-LO. I'm just curious, what do all these denote? What is the difference between them? http://www.wjjeeps.com/st_shifter.jpg


Subaru is in kind of an odd spot, and remain a fringe choice for most family-car buyers that go with mainstream makes like Toyota, Honda, Chevrolet and Ford. Part of that reason is, as you say, all their cars are equipped with AWD as 'standard', but no option to have it without. This is most certainly a performance feature in foul weather, but when it comes to lowering entry-level prices of sedans to be competitive and reaching maximum MPG's that so many drivers are concerned about, it really seems out of touch. That is why you will see more of them here where I live in Canada, where for at least 4 months of the year it is sort of justifiable, although I've never needed anything more than FWD and snow tires.

On the flipside, AWD is the new 'must have' on luxury cars, so it puts uplevel Subaru's ahead from the get-go. Companies like Acura, Mercedes, BMW and Volvo almost all offer AWD versions of their cars, which were almost non existent only 5 years ago. So this popularity of AWD in luxury cars bodes well for uplevel Subaru's. For example, in Canada the Legacy 3.6R Limited sedan sells for $$36,995 and comes fully fully loaded including nav system. An Acura TL SH-AWD starts at $49K, Infiniti G37X w/Nav $49K, etc etc etc. So as the trims climb, you actually do find good value in a Subaru.

As far as the Jeep gearbox, my understanding is limited and I'm sure someone can explain better, but it's basically all about gear ratios and engaging drive wheels. 2WD disengages power to the front wheels (on a RWD vehicle, reverse on FWD) and only uses the 2 rear wheels to provide power to the vehicle. When 4HI is selected, the front differential is engaged, and all four wheels power the vehicle with a high gear ratio, meaning the vehicle can typically travel up to 60 or 80 km/h in 4HI. 4LO uses a shorter gear ratio, and is not meant for high speeds. This short gear ratio gives maximum traction at low speeds, and often negates the need to use brakes in off-road situations. I was at a Toyota off-road test track at an autoshow a few years back, driving a new 4Runner on an off-road course. We climbed to the top of a great big hill with a steep, muddy hill on the other side. The co-pilot said "now, engage 4LO, take your foot off the brake, and let the car roll down the hill." I was skeptical...using normal gears, I would have picked up enough speed to fly off the course and into a parking lot down the road. But sure enough, the gears held the truck back, and I slowly crawled down the hill in a totally controlled manner, no brakes.

This gets further complicated when you look at locking differentials. The problem with a differential in off-road use is that once one wheel lifts off the ground, an open differential will allow that wheel to spin and not require traction on the other wheel. Thereofore, 'AWD' vehicles are useless off-road without a locking differential, because as soon as a wheel lifts, it begins spinning like mad and you go nowhwere. A vehicle equipped with 'lockers' basically locks both or all four drive wheels at a constant speed, meaning no matter how much traction you have all wheels will turn. Unless you have lockers, AWD is just for getting through snow and dirt, not off-roading.

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