People do the many of the same mods to a 540i as an M5. A 540i with brembos has better brakes than an M5. A 540i with Dinan stage III suspension has a better suspension than an M5. (M5 owners commonly upgrade to this suspension themselves) My point is that for those of us who LOVE to modify their cars, a 540i can have individual upgrades which both outperform OEM M5 equipment and provide the satisfaction of having further individualized your car. (For less $$$ than a new M5)

I won't say that an M5 is a lesser car than a completely modified 540i, however I will ask you to look at the two schools of thought on this issue... Some people like to have their race car out of the box, and some people like to create their own.

The automatic tranny has been rated to 600 or so crank HP. Dinan created a 4.4L 740iL a few years back that was a completely wicked supercharged bored/stroked/headers/etc. engine. It put down 475 HP at the rear wheels, and is still on the road today. (The car was a 1997 4.4L 7-series)

All said, the M5 is a more reliable car simply because "it came that way". Service and maintenence are standard on an M5, wheras a highly modified 540i such as mine takes a mechanic with a strong constitution. The S/C belt needs to be monitored, and the engine requires the same babying as an M5 engine with frequent oil changes (Though I'm not leakin' oil, lol) and attention to service items such as various filters and spark plugs. Nothing you shouldn't do on an M5 you care about really.

So at the end of the day, I have a car that puts down more HP than an M5 after 3500 RPM that cost less than an M5, handles better than a stock M5, is 300 lbs lighter than an M5, and allows me to take very involved sips of a tasty beverage of my choice at WOT through all of the gears. (Hey, it's the American way) Tradeoffs are a car whose long term reliability is logically less than an M5, and may well turn into a hand grenade in a few years.

Cheers,

-DanB

P.S. To say an M5 will take my car on the track is rediculous. In addition to being 300 lbs lighter, servotronic steering has absolutely no impact on my ability to direct the car around a track. By all technical merit with similarly skilled drivers, my car should actually outperform an M5 on the track as far as handling. I'm still waiting on that pussy-bauer blitz to race me... "My car ain't going on no dirt road at carlsbad! Oh, and I'm busy whatever weekend you want me to go to any track in LA"

M5 and 540 are obviously not the same cars and play to different folks. You can speed up a 540 to wax an M5 but there are more things to the M5 than 540. 540 is an awesome platform, don't get me wrong. I owned one for three years and I loved it. M5 is just the next step. You are correct about the resale. If you can enjoy your car then you effectively amortize the cost of all theupgrades needed to get M5 performance wise. Most don't keep it for very long, but if you can, then the ultimate sales price really is not that big a deal. Cheers.

I would think also that the 540i engine isn't made for the same hp as the M5 engine, so things like crankshaft/connecting rods/pistons/main bearings/dry sump pump (not present in the 540i), probably cooling system, would make the M5 engine much more robust and reliable; even though the supercharger on a 540 makes it put out almost as much hp as an S62 engine. In the "upgradable column" you need to consider drivetrain stuff like engine mounts, heavy duty clutch, gearbox, (the 540i auto transmission probably isn't made for that much hp), rear end, etc etc. And the brakes are much bigger in the M5, steering is much different (quicker ratio, more road surface feedback in the "sport mode", suspension is much different...). So on a track where your going around corners and braking, it is not much of a match...and I'd worry about blowing out the engine eventually... if you were to upgrade all that stuff to match the M5, it entire package would probably cost way more than a new M5 anyway.

The 540i is nice, but it's not a race car like the M5...