What we found

You'd think checking the pressure of the spare tyre (and the other four) would be a high priority in any car service or safety check. Obviously not. What's more, too many of the workshops skimped on doing a thorough check underneath the car.

Some garages loaded up the bill with additives and exceptionally high charges for simple items. Since when did a sump-plug washer cost $5.50? We bought a genuine Ford sump washer for $2.50 - and even the Ford parts man thought that was a bit on the high side.

Tyres

Only 2 of our 12 workshops checked the spare-tyre pressure.

We sent all our test cars in with under-inflated spare tyres. Many of the 12 spares were dangerously under-inflated, especially the space-savers.

Space-savers need very high pressures (typically 60 psi) for safe operation. They should be pumped up to 5psi more than the recommended pressure, to allow for some leakage between checks. The worst of our three space-savers came back from the service with the same unsafe pressure it went in with - just 18psi.

The flattest of our standard spares came back with its pressure barely registering on our gauge - an unusable 2psi.

We don't think there's much excuse for not checking the spare tyre.

Three of our vehicles had a punctured tyre. We sent in all three with the punctured tyre noticeably lower in pressure than the rest. The three garages didn't spot these punctures, despite the obvious clue. Only one of these garages put any air in the tyres. (We didn't create the punctures - they already existed.)

The garages did give the tyres some attention - all were sprayed with tyre reviver! We'd rather get back a dirty tyre that didn't leak.

Fluids and filters

All garages changed the oil and oil filter and most checked fluid levels. But only Honda and AA Auto service checked the brake fluid for moisture. Had other garages done this, they would have found that more than half our cars needed new fluid - either now or in the near future.

Midas in Newtown didn't check the battery fluid and one cell was down. If Midas Newtown had checked the battery fluid, it'd also have noticed the battery clamp was loose.

Extras we didn't need

Three garages used additives that we don't think are needed. Creswick Service Centre added $75.95 worth of Wynn's fuel-system cleaner and engine flush. That sure pushed up the bill. This garage is also the one that charged $5.50 for a sump washer.

Rutherford and Bond Toyota used $22.50 worth of fuel-system cleaner on a relatively new car. Its service included a complimentary wash and vacuum, which was a nice touch. But at a total cost $420.78 for the service, the owner reckons it was a very expensive car wash.

Midas in Thorndon hit us with the sell-up treatment. Would we like Wynn's Friction Proofing? $20? Our drivers had been instructed to agree to sell-ups, so this offer was accepted: we wanted to see the cost itemised on the bill.

Our view

Of the workshops we checked, we think Honda Cars, and AA Auto Service and Repair showed the best attention to detail.

Although Honda Cars' hourly rate is very high, a lot of work was done - this included changing the hydraulic-clutch fluid. AA Auto Service and Repair did the most comprehensive check, but decided the air filter was not due to be changed - we thought it was definitely due.

Honda Cars and AA Auto Service and Repair have workshops in most main centres, although we could only find one AA workshop in the Wellington area.

PitStop had the most comprehensive checklist - it closely matches ours (see Service tips) - but its two workshops missed a few faults.

The two Midas outlets we checked were quite different: one gave us a comprehensive underbody checklist, while the other seemed to do little more than change the oil and check the easy-to-see fluid levels. Midas told us the Value service we chose does not usually include an underbody check.