Almost four in every 10 motorists say they service their own cars - as long as it was built before 1999 - a survey by Kwik-Fit revealed.
More people say they are maintaining their own vehicles, but most of them admit they may not be making a good job of it.
The firm's survey spoke to 2,000 adults in the UK and found that people seemed to be more confident in their ability to service their car if it was an older model.
As much as 37% of those with cars from 1999 or earlier said their vehicle was simple enough - 6% of those with cars from 2007 to 2010 said the same.
Kwik-Fit's David White said: "Modern cars are increasingly reliant on computer technology so there are fewer tasks under the bonnet suitable for an amateur enthusiast as they won't have the necessary equipment.
"Car owners shouldn't rely on the MoT to pick up faults as this mainly focuses on safety factors. A proper service will highlight issues which could cause a future breakdown and also cover areas too complicated for most DIY mechanics."
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