My 2004 BMW 325XI has been unstoppable in the snowy weather, but it's
horrible on gas.
 I've thought about replacing it with an Accord or Camry with Blizzaks
or some other really excellent snow tire.
 How much am I giving up here?

 Some factors:  Lower NY state climate (suburbs of NYC), and the fact
that I have to drive *during* the day from client to client, averaging
four to eight stops in a day.

 I'm self employed, so every day I'm not on the road due to snow is a
money-losing day.

Hi again...

I can only tell you from experience that I've been in a Honda Accord
in the middle of winter on a mountain in New Hampshire, and couldn't
believe how easily it scooted up a road with a 30-40% incline, and 
six to eight inches of accumulated snow. I think it did have chains 
on, and any skidding was easy to ignore, since you just needed to 
point the wheels in the direction you wanted to continue and away 
it went. No muss, no fuss.

sublime1-ga

Sublime,

Thanks for the comment, but the suburban area I'm in (Westchester
Cty), prohibits tire chains.  Not sure if I want to bother
removing/replacing them constantly anyway.

Anyone else with a perspective on this?

I don't know enough to really answer this question since I have never
had snow tires (although I covet them and have read a fair bit about
them) and I have never driven on the East Coast.  But, I have driven
front wheel and 4-wheel on snow a fair bit (although only a little
all-wheel).  With a little attention to conditions, even with regular
tires, front wheel drive is enough to get you through anything but
really exceptional snow conditions in areas that are plowed at least
intermittantly.  Add snow tires (which I have read are a real treat to
drive with in snow and probably better than 4-wheel drive with regular
tires) and front wheel drive would probably be good enough for even
the 5 year blizzard on surfaces that are plowed at least
intermittantly, although I would still have adequate survival gear to
wait out a blizzard stored in the car.

However snow tires are not cheap, don?t last forever, and need to be
changed twice a year and stored in between, so they are not without
their own issues.  Why not have your cake and eat it too, with a more
fuel efficient all-wheel car?  Of course, a more fuel efficient car
will be smaller, lighter (which changes snow driving), and closer to
the ground--even four wheel drive doesn?t work that well when the snow
is really deep and none of the four tires are touching because of the
snow packed under the car.  Makes you into a post turtle.

I lived in the Sierra Nevada mountains for eight years, in a ski
resort town at 8000ft elevation, average snowfall 400+ inches per
year.  Snowstorms that didn't measure in FEET didn't even cause me to
put on my winter boots.  And for the first three years there, I drove
a 1989 Toyota Corolla SR5, front-wheel-drive, with ordinary M+S (mud n
snow) tires.  M+S tires don't have to be taken off and stored in the
summertime, they're good year-round.  The ONLY time I needed chains
was to get up my steep, steep driveway when the plow hadn't come after
a storm -- not because of the snow, but because other drivers in the
apartment complex had driven on the snow, compacted it, and turned it
into ice.  On regular town streets I never had any trouble at all.
ONE CAVEAT -- remember your low clearance!  Snow berms at driveway
entrances can be treacherous and leave you high-centered if you're not
careful.  But if you're careful, the front-wheel drive should be fine.

Get a Subaru 2.5RS. Good looking, sporty, and great on gas mileage.
Plus it has a very identical engine to the WRX STI (the big nasty
one), just minus the turbo and a lot of go fast parts. It is a proven
car with great AWD and capable of sporting around town and taking the
abuse given to it. Or, if you have the money and really love the
speed, get a WRX STI or a Lancer Evolution. These cars are basically
rally cars which thrive in the snow. If you haven't had the chance to
drive one, do so! AWD is a term thrown around way too often to
describe inadequate systems. Go with the masters of AWD and you will
be doing 80 in a foot of snow not thinking twice about it.

Car & Driver had an interesting article a few months ago where they
fitted their AWD Porsche w/ snow tires. They said it handled better
than any SUV in the snow and was far quicker.

To answer your question bluntly... Nothing.  There is not a
"scientific" answer to such a question. I agree with most of the
thought so far given.
One thing I might add, 4x4 adds TRACTION whereas winter tires add
ADHESION. That said, here's what happens, in order to get your car up
to speed the 4x4 is going to do the trick regardless of what tires you
have (to some extent). When you need to stop it's a whole different
story. The brakes are going to apply friction the the wheel and tire.
The friction needs to be effectivly transmitted to the pavement hence,
good tires.

That said, choose the right ones...

"snow" tires get a good grip like 4x4's and will get you up to speed
in deep powder. "ice" tires have a softer rubber composition and will
adhere to a slippery surface well in lower temperatures.
frankly, I prefer "ice" tires. Most roads are plowed pretty well so
your biggest threat is from cold weather and ice.

Keep in mind that not being able to advance quicky is one thing but,
not being able to stop can be deadly!

Blizzaks?...great!
Nokia?...even better!
Michelin Ice...great too!

Happy motoring!
__Peter Quebec, Canada (need I say more?)

As a professional, involved with advanced driver training, I can state
that all wheel drive is a bit over-rated. All wheel drive will
certainly help you accelerate better in snowy or icy conditons but it
will provide NO BENEFIT when it comes to braking or cornering.

For the best control under snow and/or icey conditions the type of
tires you use really makes a huge difference. When I say "huge
difference" - I mean just that. Absolutely a night to day difference
in performance.

See my comments and others at this google answers link about snow tires:

http://answers.google.com/answers/threadview?id=583750

Hi,
    You should definately check out some good snow tires.  I live in
Maine and I can tell you that without these babies my cars would have
seen the broad side of a tree plenty of times.  I had a mustang cobra
on snow tires, and with smooth driving she was fine all winter, in
fact, m uch better than expected.  Performance tires really aren't
going to right here, and all wheel drive only works if you drive
properly anyway, but for condition driving, snow tires are key.  Check
out http://www.carperform.com/cgi-bin/index.pl?=&=G6H1Are for some
good info too.

A few things. I have been driving front wheel drive cars, 4 wheel
drive and all wheel drive cars and trucks for the last 30 years. Are 4
wheel drive and all wheel drive vehicles better in the snow? Yes. Is
it a big difference? Yes! Those who say there isn't a difference or it
is very minor have either never driven such a vehicle before in REAL
snow, or they are intentionally knocking them for some unknown reason.

They will get you going safer driving straight, and are also better
around corners.. period! There is simply no comparison between the
two, and simple logic would explain why. I live in northern Canada
where we get snow, sometimes very heavy snow for the majority of the
year. 80% of the vehicles here are either 4x4 or all wheel drive. Even
the police here use all wheel drive SUVs almost exclusively, and they
wouldn't do so if there was only a minor difference. The only people
here who drive 2 wheel drive cars are those that don't have to travel
far or don't travel during heavy snow.

But.. with that said, 4 wheel drive WILL NOT help you stop any faster.
All cars have 4 wheel braking and caution must always be used to come
to a safe stop.

If you are unable to get a 4 wheel or all wheel drive vehicle, your
next best choice is a front wheel drive with good snow tires. If you
drive a lot in deep snow I would recommend a new product called
SnoClaws.
http://www.flextrax.com/?r=snoclaws
They are a type of tire chain, except they are made of rubber so they
are legal everywhere. You can put them on your tires in about 5
minutes and take them off in seconds when you don't need them.

Hope this helps

After I did a drift turning with Subaru SUV(basic model) on the snow
in the parking lot, I realize the "hitting curb thing" won't happen if
my acura 1.7EL is a All wheel drive. That thing cost me over thousand
bucks to repair.
My suggest: Get All Wheel Drive.