First off I would like to say this car has been in the family since new, that said, I know most of the service/maintenance history.
The taillight died on me around 78K miles, this was about $400 for a new OEM (original equipment manufacturer) assembly.
The splash guards under the front end before the wheels were damaged, and replaced at 78K miles for about $100.
The little button on the seatbelt that makes it so when you take it off the belt only falls half way, and not to the floor fell off. It was only approx. $20 to replace, but while it was broken it was hard to reach between the door and the seat to find the little seatbelt head!
Front brake assemblies needed replaced at about 76K miles, and ran approx. $800 installed.
About 45K miles the front left headlight needed replaced, and while I don't recall the cost, but I know it was high!
All air filters (cabin air purification system) were replaced at the 80K mile service, as well as a lot of other basic maintance. The cost was pretty high, but they also tuned everything up, new air filter, and a bunch of little things like that.
I also somehow cracked the radiator side (it was a cheap piece of plastic and it broke along the molding). This little crack was in the side of the retaining tank. The entire radiator was pulled, and new reinforced composite components were installed onto the sides. This whole procedure with reinstallation was about $600, but should not have to be done again. Apparently this is a fairly common BMW flaw... I don't really know.
Hood emblem needed replaced, as the paint all started to chip off around 68K miles, the installation would run about $150 with parts. This you can do yourself with a flat head screw driver, and a cloth. It takes about 10 minutes, and you can buy the parts from any bmw auto supply company, or even on ebay for about 20-25 bux! I supplied my own parts, and they put it on for me at the 80K mile service for $21. I figured let them mess with it!
This car rides very nicely. Unlike the 740iL models the 740i from 96-98 came standard with a lowered front end, and sport suspension. The sport package upgrades the 16 inch wheels to slightly larger "M-parallel" rims, normally found as stock on the M5 of those years. The 740iL was not set up the same as their shorter wheel base counterparts, so if you wanted the lower, more aggressive look, then you needed to go with the sport package.
The 740i weighs in at 4250 with a spare tire and a full tank of gas. At that weight the little 4.4L V8 is still capable of getting 282 HP down to the wheels, and shooting the car off like a rocket. Stock wheels and tires will get you from 0-62 MPH (0-100 KPH) in about 6.7 seconds. If you upgrade tires this can drop down to about 6.1 seconds, and even less if you get the proper wheels. Change your air intake, or even upgrade to a high performance, low resistance, K&N air filter and you can enhance it even more!
Today I have seen people changing exhaust on the e38 (1996-01 7 series), as well as doing several other modifications. From the facelift with the 99-01 style headlights on the 96-98 models, to full out Hamann body kits and wheels.
I find this car to be much more comfortable than most, yet much more sporty than the 745i or 745Li.
If you want the V12 engine then BMW offered the 750iL (now replaced with the 760Li) and while it has over 300HP its acceleration is a little slower than the V8. It is heavy, guzzles gas, and is not as fast, but has a great sound to it! Not to mention the V12 is amazingly smooth and refined, obviously more so than the V8 once you start cruising at around 150 MPH.
The 7 series are all about the same in price, so you can decide if you want the V8 or the V12 now for about the same price tag. Just keep in mind the bigger engine is about 75% more expensive to maintain, and is less reliable. Not to mention the fact that it has the normal BMW maintenance costs for the rest of the car!
The steptronic transmission is nice, and allows you to shift if needed while still being in automatic. This means for faster stopping or acceleration it can be used. Left in automatic it will still shift and not cause engine or transmission damage. If you switch it to manual it will allow you to over rev if you aren't careful, and it is easy to forget to shift! I have found a car you dive in auto normally is hard to shift as a manual as there is no clutch, and you are not used to the extra thought involved in shifting. If shifted into 4th gear in automatic it automatically goes into "sport mode" which is more more sport oriented driving (ie, more aggressive). It can be left in 4th at all times for a better RPM range and acceleration, as well as faster downshifting, and some braking assistance when letting off the accelerator. It is, on the other hand, a much fuel efficient mode and not for the driver looking to be green friendly!
This is a very easy to drive car with the advanced traction system left on and is pretty forgiving. Take the traction computer off and it is a very different machine! You notice the overpowered steering associated with most Porsches! The back end can break loose (especially if you take the traction off as well as use the sport mode/steptronic), and it is no longer designed for use by an amateur road driver!
For you power heads I have a story... after prom night at 2AM I went to the local Home Depot parking lot. It was empty completely, and there was no risk of an accident so I figured it was safe. Putting the car in low gear sport mode, and switching the traction off I turned the wheel and nailed the gas. I did 3 complete 360's before I decided I wanted to keep my tires intact! These were full burn outs... smoke everywhere, the tires screaming the whole way around! This was not anything you could do in a Honda, that's for sure! This car is a true RWD rocket!
The hardest thing I have found with this car is keeping the supreme sound package on low, and not speeding! A great, fun, fairly reliable car! The repairs are pricey, but what you would expect from any BMW.
One complaint is that the bass in the sound system (even the factory premium system) is a little lacking in the low range. Trebs are great, but that low end bass just isn't there! The rest of this 12+ speaker system is amazing!