IMO, it is every bit as reliable as the 302 it replaced.  In many ways
it is even better and more durable.

The 4.6 Modular is a very nice motor; it's very durable and very
reliable. The SOHC 2V 4.6 has been in fleet service in the Crown Vic
since 1992 and it's got a pretty good reputation in that arena with
vehicles that put on hundreds of thousands of miles per year. The DOHC
4V 4.6 has been in the Lincoln Town Car since 1993. Both motors have
been in the Mustang since 1996.

The current SOHC 3V is different up top (variable valve timing, 3
valves per cylinder) but the same motor down low. However, obviously,
no one can tell you about their 20 year old mod motor'd Ford :). I can,
though, tell you that I know cops that have put 250,000 on their CV's
and they were still happy with their cars when they turned them in. And
I know several Mustangs with SOHC and DOHC with 120,000 miles and they
are still running very well.

There's not much on the horizon for Mustang. The new VVT, 3V V8 motor
is the latest of the Ford Modular line. The upcoming SVT Shelby GT500
will be using a supercharged DOHC 4V 5.4 motor, essentially a cast iron
block verion of the Ford GT motor. The current Mustang also has a new
V6 but I don't know as much about it.

Dan
2003 Cobra convertible
With some stuff and things

an J.S. wrote:

I've heard many sing its praises.  The SOHC 4.6 version in the last cab
we took home from bar night had 315,000 on it.  The guy bought the car
new rather than get a used police interceptor, took care for it, and
said it was just starting to show signs of being tired.  The second
tranny he had in the car seemed a little sloppy, but what do you want?
He bought the civilian Vic new for better mileage, and so he would know
how it had been treated.  He knew people who got half a million out of
both the hard-driven PI and civilian Vic motors.  I think the PI has the
5.4-liter modular.  I got phone numbers for used cop car dealers from
him, since I am considering the Vic, Marquis or the PI to replace my 2.3
Tempo with 201,000 on the untouched longblock... still getting 28-30 mpg.

I'm sure many others in this group can attest to both the SOHC and DOHC
versions of the 4.6 having taken many hard miles and not having given
them problems.

Many were and still are enamoured with the old pushrod 302 and 5.0
engines and rightfully so; both the early 302 and roller-cam "5.0" was
undoubtedly one of the best motors Ford ever made.  But I've never heard
angry screaming about the 4.6 that replaced it... I heard skepticism
from Mustang fans 10 years ago, but that's only natural.  Thankfully, it
doesn't seem it was actually warranted.

as others have noted, there are so many different versions of the 4.6
it's hard to project the long-term prospects of the "stang GT version.

I'm no gearhead, but based my purchase of one on a process of
elimination:

 no more front-drive (one Chrysler was enuff - so that eliminated most
affordable new cars).

 both 'stang engines hsve timing chains, not a belt.

 I'm not wild about aluminum engines, but trust the V8 as block and
heads are aluminum......I believe the 6 is iron/aluminum......and I've
always had head gasket, leak problems on "bi-metal" engines  I hope Ford
isn't using as many plastic engine parts (like GM).

 Finally, hoping the EPA figures are at least relative if not
realistic......the 8 is rated as getting only 1 mpg or so less than the
6, so based on the few thousand miles a year I plan on driving it, guel
cost wasn't a consideration.  ('though insurance cost may turn out to
be!!!)

FWIW.
I'll add one more post to this thread and I'll probably shut up. If
there is one thing
that the COP (coil over plug) engines have that is somewhat
troublesome, it's the coil.
If you take it to the dealer to have it replaced, it's about $100 per
coil. Aftermarkets may
be cheaper. The irony to all this is that it's usually not the coil
that fails, it's the spark plug
boot. You can get replacement spark plug boots pretty cheap and that
usually fixes the
problem. The 4.6 modular engines came with or without the COP setups.
My $.02 worth.

BTW, by your post you obviously drive foreign brands and you are now
looking at a domestic. What made you look? (Just curious)

They are reliable but nobody can tell yet what the new heads on these
engines will do. Part of the outcome will be how you treat it. regular
oil changes, taking it easy on the engine until fully warmed up, etc
etc.