Hi, I had a 2005 3.0 (07-14) and now have an M roadster (since Dec). The 3.0 was a good car and was pretty quick. I’d expect the Si (w/30bhp more) would be a really nice car. However, as an occasional car, the M is a far more special thing. The steering on non-M Z4s is pretty awful and run-flats make the ride worse than the M version. You can change the tyres, but you can’t really do much about the steering. The S54 engine is a fantastic thing and combined with the hydraulic steering and non-runflat tyres turns good to great.
The downsides (as previously mentioned) are the higher running costs. The valve adjustment is the major cost for scheduled maintenance and you’ll probably lose the car for a couple of days (the engine needs to be cold to do the job). Probably a £700-800 service with spark plugs (these are £18 each!).
Then you have what is technically preventative maintenance, but should called be inspection III, changing the big end bearing, which is every 60-80k. This is typically a £1k job.
Brakes are also very expensive compared to non-M Z4s. Front discs and pads are £500+, rears are £400+ for the parts, so over £1k to change them all. There isn’t a cheaper OEM spec option either. Non-Ms have loads of quality aftermarket options, even the BMW are quite good value, especially on 4+ menu pricing.
You should also treat the S54 with a lot of mechanical sympathy. It is a fairly exotic engine, so should be fully warmed up (oil temp is critical) before any significant load is put on it. With 10W/60 oil (and an iron block) this can take quite a while in the cooler months. Great if you are going out for a fun drive, but not so great for commuting in busy traffic.
The M54 and N52 are normal engines designed for use in BMWs saloon and SUVs. These are all aluminium or magnesium alloy, with light weight oil and lower redline. The heat up quick and don’t need the kid gloves that the S54 needs.
If you have the budget, the Z4 M is the best choice. For a roadster, £12-16K + £2K reserve fund is a good budget.
You’d be looking at £6-7K for an earlier 3.0 and £8-10K for the later 3.0 Si. You’ll probably need £1k in reserve.
The steering can be problematic on the non-Ms and can be as simple as lubrication(cheap / free), but could be a new / replacement column. This can be thousands.
Mine was £14.3k, 60K with FSH from a dealer. It was a trade-in at a main dealer that couldn’t go on approved used scheme due to age / mileage.
I’ve spent about £1.5k on it so far, new rear springs, tyres, M-badges (£100 for the trio), oil and filters, two throttle position sensors and a cooling fan. I’m going to get the bearings replaced later in the year and it will need an inspection 2 next year.
I saved a bit on the first failed throttle sensor and cooling fan. The sensor is cheap, but you have to remove the intake plenum which takes a few hours. The fan is expensive, but takes about 30 mins. I did the sensor myself so saved the labour, probably £200-300 and for the fan, rather than buying BMWs £700 part, I did a bit of research and found that one from a six cylinder E60 would work. Thankfully Mahle offers an aftermarket one for £250. All I had to do was remove the fan module from the E60 shroud and bolt it into my existing one.
So, you can help keep the costs down if you are prepared to do a bit of the work yourself.
Finally, I believe the Ms (and Alpinas) will be a better long term investment. The money you put in will be less than the longer term appreciation. If you look at other Ms and their non-M counterparts, you’ll notice the Ms bottom out, then appreciate gently for 5-10 years, then jump massively. It’s only once the big jump occurs so the non-Ms start to appreciate, as the Ms become out of reach. It’s not even a rarity thing either, I bet there are more E28 M5s than there are E28 525e still with us, but an E28 M5 would be 5-10x the price
Attleborough, Norfolk
North West Surrey
