Used car buying guide: Porsche 928

If that original 1978 car was a revelation, the 1980 S that followed it was teetering on the verge of magnificence. However, from the S4 onwards, there was just the suspicion that the omelette was being over-egged, and over the years the 928’s suavity was debased as it became raunchier, faster, harsher and a little more uncouth. Either way, a used 928 is still a desirable thing today. 

History shows that, despite Porsche’s original intentions for the 928, it was the 911 that prospered. Porsche, always good at doing the wrong thing the right way, developed its rear-engined wundercar to the point where criticism of its inherent solecisms seemed churlish. After all, that very first electric Porsche car had its engine at the rear, so we could have seen which way the wind was blowing way back then. 

What we said then

28 October 1978: “From a standstill on a dry, well-surfaced road, there is no wheelspin; the car just takes off to reach 50mph in 6.3sec, 60mph in 8.0sec, 90mph and the quarter mile in 16.2sec and 100mph in 20.1sec. The 928’s natural attitude ultimately is understeer, accompanied by tolerable roll. It is possible to break the back away if you lift off in a bend, but you’ve got to be going very quickly. It is remarkable how well the car rides. The 928 combines performance, practicality and the safest of road manners to a degree unmatched by any other supercar. You could call the 928 a grown-up supercar.”

An owner's view

Andy Jeffreys: “I bought one of the last 928 GTSs ever made in 2003. It had hardly been used and was in perfect condition – beautiful, if at that point hugely unfashionable. By far the most fun trip I ever took in it was to drive from Beirut to Istanbul. The low chassis struggled across the poor roads and the car finally surrendered as we arrived in Aleppo – not because of the terrain but because the local petrol was of such low quality. Overall, though, my 928 was a terrific way to get around: smooth, stylish and fast, with enough space to make it a decent grand tourer. The biggest regret is selling it in 2008 for £3500, no question the worst financial decision of my life.”

Buyer beware

Engine: Smoke when warm hints at worn valve guides and cylinder bores. Check the oil level. Lumpy running could be a worn distributor or failed ECU. Vibration at idle may be worn engine mounts. Timing belts, tensioners and water pumps should be changed every 60k miles or four years. Check for coolant leaks. Well-maintained engines should exceed 150,000 miles without a rebuild. 

Transmission: Check that the torque tube connecting the gearbox to the diff isn’t putting pressure on the flywheel mounting plate. Examine the underside of the automatic gearbox and torque converter for leaks. The rare manual ’box has a notchy change but too much stiffness can wear out the synchros. The three-speed and four-speed automatics are Mercedes-Benz units and require little more than an occasional fluid and filter change. The transmission was steadily updated, especially the manual, which had multiple changes to the clutch, gearbox and torque tube. The clutch was twin-plate at first and changed to single-plate on the S4.

Brakes, steering and suspension: Check the brake lines and hoses, steering and driveshaft gaiters, and suspension arms and bushes. Clonking could mean worn bushes. The rear brakes can seize through lack of use. The suspension is very robust and only the front upper wishbone bushes give any trouble. Original Porsche dampers are expensive, but gas-filled replacements can be sourced.

Body: The galvanised 928 has aluminium doors, front wings and bonnet but check for bubbling around windows and rear hatch, and the underside for corrosion. Tired sunroof and tailgate seals can cause damp carpets.

Interior: Check all the electrical systems work. Complex electronics will play up with age and neglect. Early cars had half-leather or vinyl trim with ‘Pasha’ chequered velour centres: it’s desirable now, but most buyers preferred later full leather.

Also worth knowing

A coolant change every four years or so can reduce internal aluminium corrosion, while the brake fluid on a classic should be changed every two to four years. Coolant leaks aren’t uncommon and a replacement radiator is hugely expensive.

One of the largest running costs for a 928 will be fuel. You’re unlikely to better 12-15mpg in an S4 around town and 18-20mpg on a run, so you’ll need to keep some money back for those sunny days.