Iv got a mate with a 350Z so i lurk on that forum too, just came across this topic where the owner has broken down the ownership costs over a 4 year/100k period and i thought it was quite intresting (if a bit scary), just wondering if there are any higher milage boys on here and how the Z4 compares? 
..............................................................
Total Costs over 100,000 miles:
Hardware
350Z GT with RAYS alloys, Alezan Leather, Supaguard and Phone Kit (18/12/2003)
£28,561
350Z Valve Caps, Car Cover (18/12/03)
£292.49
Nissan mats, trunk net (20/12/03)
£100.17
Subtotal: £28,953.66
Servicing
Nissan High Mileage Service Plan:
£1031.19
FP1 (8/3/2004 @ 9,059 miles)
Included in Service agreement
FP2 (10/7/2004 @ 18,838 miles)
Included in service agreement
P1 (2/12/2004 @ 27,010 miles)
Included in Service agreement
FP3 (30/4/05 @ 37,362 miles)
Included in service agreement
FP1 46,621 miles (and brake fluid change) (31/8/2005)
Included in service agreement
Rear Brake pads replaced (£234.41)
FP2 (23/1/2006 @ 53, 775 miles)
Platinum spark plugs replaced.
Included in service agreement
FP1 (16/6/2006 @ 62,182 miles) (oil supplied)
customer supplied clutch fluid changed, replacement of auxillary drive belts
£284.45
FP3 (14/9/2006 @ 71,042 miles)
Flwheel + Nissan Clutch + Windscreen wiper arms + replacing customer supplied brake fluid
£1615.47
FP1 (24/2/2007 @ 78,039 miles)
£87.94
FP2 (3/8/2007 @ 88,796 miles) (own engine oil and gearbox oil)
+ change gearbox oil
£231.69
FP1 (5/12/07 @ 99,448 miles) (own oil supplied)
£76.96
(+£15.39 to replace customer supplied differential oil)
Subtotal: £3579.50
Consumables and Non-warranty/non-scheduled maintainence
Nissan Clutch, cover, clutch release bearing and fitting (15/10/04 @ 23,388 miles)
£543.32
Fitting of tyres *2 rear (Hi-Q Motorway) (22/1/05)
£35.25
Supply and fitting of front brake pads, supply and fitting of rear parking sensors (painted at body shop), loan car (14/2/2005@ 32,055 miles)
£670.42
2* Pirelli P Zero Rosso (225/45 R18) (Hi-Q Motorway) (4/3/2005)
£313.21
Nismo clutch, Nismo Clutch Cover, Clutch Release bearing (Ordered from Performance Nissan, USA) (30/4/2005 @ 33,222 miles)
US$ 693.15 + Tax/Duty
£305.50 (fitting)
Fitting of 2 tyres (Bower Lane Tyres) (31/8/05)
£28.20
Nissan Clutch, Nissan Flywheel, windscreen wiper arms (15/9/2006 @ 71,042 miles) (own oil supplied)
see servicing FP3 for costs
Passenger window regulator, passenger door trim, driver's seat belt and fitting (28/9/2006 @ 71,843 miles)
£1606.99
FP1 (24/2/07 @ 80,359 miles) (own oil supplied)
£87.94
Coolant (31/5/2007)
£9.98
Subtotal £4100.81
Insurance
Estimated at £700*4
£2800
Petrol
100,000 miles at estimated 22 mpg at estimated £1.00 per litre:
17901 litres
£17,901
Special note regarding clutches:
My last clutch (an OEM Nissan clutch, flywheel and cover) is the first clutch which has felt normal in my car; it has lasted considerably longer than the initial Nissan OEM ones, and interestingly, is the only clutch I have used on a driver training day, or at the Nordschleife.
GRAND TOTAL (not yet complete, some items, e.g. tyres, brake pads and one set of brake discs missing):
£57,334.97
Current value of car (Parkers: private sale: (100,000 miles) Good Condition: excluding satnav)
£11,195
Cost over 4 years= £46,139.97
Cost per mile= 46 pence
Driving experience: Priceless
..............................................................
Total Costs over 100,000 miles:
Hardware
350Z GT with RAYS alloys, Alezan Leather, Supaguard and Phone Kit (18/12/2003)
£28,561
350Z Valve Caps, Car Cover (18/12/03)
£292.49
Nissan mats, trunk net (20/12/03)
£100.17
Subtotal: £28,953.66
Servicing
Nissan High Mileage Service Plan:
£1031.19
FP1 (8/3/2004 @ 9,059 miles)
Included in Service agreement
FP2 (10/7/2004 @ 18,838 miles)
Included in service agreement
P1 (2/12/2004 @ 27,010 miles)
Included in Service agreement
FP3 (30/4/05 @ 37,362 miles)
Included in service agreement
FP1 46,621 miles (and brake fluid change) (31/8/2005)
Included in service agreement
Rear Brake pads replaced (£234.41)
FP2 (23/1/2006 @ 53, 775 miles)
Platinum spark plugs replaced.
Included in service agreement
FP1 (16/6/2006 @ 62,182 miles) (oil supplied)
customer supplied clutch fluid changed, replacement of auxillary drive belts
£284.45
FP3 (14/9/2006 @ 71,042 miles)
Flwheel + Nissan Clutch + Windscreen wiper arms + replacing customer supplied brake fluid
£1615.47
FP1 (24/2/2007 @ 78,039 miles)
£87.94
FP2 (3/8/2007 @ 88,796 miles) (own engine oil and gearbox oil)
+ change gearbox oil
£231.69
FP1 (5/12/07 @ 99,448 miles) (own oil supplied)
£76.96
(+£15.39 to replace customer supplied differential oil)
Subtotal: £3579.50
Consumables and Non-warranty/non-scheduled maintainence
Nissan Clutch, cover, clutch release bearing and fitting (15/10/04 @ 23,388 miles)
£543.32
Fitting of tyres *2 rear (Hi-Q Motorway) (22/1/05)
£35.25
Supply and fitting of front brake pads, supply and fitting of rear parking sensors (painted at body shop), loan car (14/2/2005@ 32,055 miles)
£670.42
2* Pirelli P Zero Rosso (225/45 R18) (Hi-Q Motorway) (4/3/2005)
£313.21
Nismo clutch, Nismo Clutch Cover, Clutch Release bearing (Ordered from Performance Nissan, USA) (30/4/2005 @ 33,222 miles)
US$ 693.15 + Tax/Duty
£305.50 (fitting)
Fitting of 2 tyres (Bower Lane Tyres) (31/8/05)
£28.20
Nissan Clutch, Nissan Flywheel, windscreen wiper arms (15/9/2006 @ 71,042 miles) (own oil supplied)
see servicing FP3 for costs
Passenger window regulator, passenger door trim, driver's seat belt and fitting (28/9/2006 @ 71,843 miles)
£1606.99
FP1 (24/2/07 @ 80,359 miles) (own oil supplied)
£87.94
Coolant (31/5/2007)
£9.98
Subtotal £4100.81
Insurance
Estimated at £700*4
£2800
Petrol
100,000 miles at estimated 22 mpg at estimated £1.00 per litre:
17901 litres
£17,901
Special note regarding clutches:
My last clutch (an OEM Nissan clutch, flywheel and cover) is the first clutch which has felt normal in my car; it has lasted considerably longer than the initial Nissan OEM ones, and interestingly, is the only clutch I have used on a driver training day, or at the Nordschleife.
GRAND TOTAL (not yet complete, some items, e.g. tyres, brake pads and one set of brake discs missing):
£57,334.97
Current value of car (Parkers: private sale: (100,000 miles) Good Condition: excluding satnav)
£11,195
Cost over 4 years= £46,139.97
Cost per mile= 46 pence
Driving experience: Priceless