Following on from the letter by Sam Connell a couple of issues ago about engine capacity and reliability, I am thinking of replacing my wife’s Renault Clio with a new one, and I’m concerned about the reliability of these new small capacity engines. I worry that the extra complexity of the turbocharger and ancillaries is going to have an impact on running costs and longevity over a conventionally sized small car with around 90bhp, like the 1.4-litre 16-valve petrol engine in my wife’s present Clio. Should I be worried, and are car makers over complicating things in the quest for greater fuel efficiency that is ultimately quite difficult to achieve in the real world? 

Bob Miller

Interesting thoughts Bob. In the years that I’ve been involved with diesel, there’s no doubt that their engines have become more complex, but fundamental reliability issues have not really increased. Yes, there have been problems with emission control equipment, but things seem to have settled down generally. In the meantime, in the search for better economy, petrol engines have become more complex and smaller, and hard-working petrol engines with turbochargers are becoming the norm. But the series of Renault/Nissan diesel engines that the Clio uses, particularly the sweet and flexible 1.5-litre dCi unit, have been improved and refined over the years to a very high level of reliability and their emissions control systems are some of the very best and most trouble-free in the business.

I think that Renault possibly learned quite a lot from sorting out the issues with the troublesome exhaust gas recirculation systems in the Laguna 1.9-litre dCi engines some years back. So I would encourage you to go and look at a diesel Clio, which is a fine car, with the reservation that your wife does need to do some fairly regular 10 miles plus journeys. If it is just for trips to the local shops and the engine never gets a decent run, then maybe a petrol engine or even a hybrid would be a better choice.

Doc