I’ve owned an E39 540i/6 and E39 M5 together for almost 3 years now. I often get asked what the differences are between the two and why I have both. Here’s a quick and dirty answer to that question!
I live in Canada and it gets cold in the winter here, VERY cold. Also, they salt the roads like crazy. I store my M5 in the winter and drive the 540i instead… It’s still -13C outside today and I simply can’t wait to take the M5 out of hibernation. That should tell you all you need to know, compared to the 540i the M5 does not disappoint. The actual driving experience is just that little bit better across the board. Compared to a 540i Sport, the M5 is better in most ways.
- More power (duh!)
- Limited slip differential
- Faster steering ratio
- Interior trim options (two-tone seats, aluminum sport trim, M-Audio package)
- Better brakes (slightly, US-spec brakes are single piston and are pretty terrible actually)
- Dynamic thermostat (thermostat can be forced open during warm-up and for rest functionality)
- Less Costs ~20% less to maintain on average
- Has full size spare compared to M5 with no spare tire due to exhaust routing
- Doesn’t burn oil like the M5 (later model 02′ – 03′ M5s have better rings though)
- The 10W60 oil makes the M5 a bad winter car – run thinner oil in the winter if it gets cold where you live
- The M-sport steering wheel is not heated
More Similarities than differences
Otherwise, almost all other parts are completely shared: same transmission, nearly identical suspension (M5 engine is a bit heavier so they have a slightly different spring rate to compensate), same electronics, etc.
Which to choose?
I don’t know if this is true, but one anecdote sticks with me when comparing these two beasts… At some point, an M5 owner met one of the E39 engineers at a BMW-hosted track event. He asked the engineer if he could run 5W30 oil in the M5 without any negative effects. The engineer thought about it for a few moments and replied “Sure you could if you drive the M5 like a normal car and don’t push it too hard. If you want a powerful, comfortable commuter car, we make one of those too – the 540i.” I’d say the focus between the two cars is clearly different in this way. If you want something a little sportier, the M5 is your answer. If you don’t feel you are able to ever push the handling and power limits of the 540i then I’d say it’s probably the better car for your needs.
I couldn’t choose between them so I ended up with both