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Hi Dermot,

If you mean actually physically swapping out the engine and plumbing in a diesel then I wouldn't recommend it. Diesel engines are much heavier than their petrol counterparts and most car makers tweak the suspension, brakes and steering to allow for that fact. Putting a diesel lump in where a petrol one was could upset that delicate balance. Also, it's an enormous amount of expense and hassle to do so, when you could just trade in for a similar model with a factory-fit diesel.

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Hi Dan,

Hmmm. Generally for your mileage I would recommend a petrol car, but the bad news is that in your size bracket, petrol engines are a little thin on the ground. You could go for either a straight replacement for your Corolla by getting a Toyota Auris 1.4 D-4D, which is a very fine car, or you could, as you suggest, branch out and snap up a Hyundai i30 1.6 diesel - again a very fine car and with that five-year warranty, a very tempting buy. 

But, with your mileage profile, I would suggest taking a good long look at petrol alternatives. The Ford Focus 1.0 EcoBoost is a terrific car with a great engine and well worth a look. That said it's a little tight in the back seats for two teenagers so I'd say the best all round bet is a Skoda Octavia 1.2 TSI. It's more affordable than the diesel version, damn near as economical and has a big boot and lots of space in the back seats for those teenager-filled weekend runs. Great quality and reliability too.

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Hi Michael,

It kinda depends on the spec of the cars in question. If, for instance, it's a 2.0 160hp Insignia versus a 110hp 316d, then go for the Opel. If it's a 320d, then go for the Beemer.

Come back to us in the comments if you'd like more help.

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Hi Jean,

Tricky to say, I'm afraid, as the trade-in value offered by a dealer has as much to do with their business model and circumstances as it does with any intrinsic value in the car. It also of course depends on the car you're trading it in for. If it's something that's sticking to their forecourt, they'll be more keen to offer you a good deal to get shot of it. Values for a 5 Series like yours seem to vary from around €27,000 at the high end to low-twenties for higher-mileage models. You can knock off around €1,500 - €2,000 from that for the dealer to build in a margin and defray any costs of preparing the car for sale, so your trade-in should range from around €20,000 to €25,000, but that's a best guess and nothing more.

Try and have a ring around (or better yet, a drive around if you have the time) to various dealers and try and get them to give you a rough idea of what they'd give you for the car.

Do let us know how you get on,

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Hi John,

Yup, a small diesel sounds like it should be ideal for you. Depending on what kind or size of car you need I'd recommend either a MINI Cooper D 1.6 (small and sporty), Opel Astra 1.3 CDTi (slower, but more spacious), Toyota Auris 1.4 D-4D (similar to Opel but probably more reliable) or that old favourite the Volkswagen Golf 1.6 TDI BlueMotion (ultra economical). Or, if you need more space how about a Skoda Octavia Combi estate 1.6 TDI or a Citroen C4 Picasso 1.6 HDi?

Help us with your needs and we'll narrow that down a little!

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Hi Katy,

Expert answer

Hi Danielle,

An updated Polo is indeed imminent, but from what we've seen it won't be a massive change from the current car, certainly in terms of styling, and the only major mechanical change will be the addition of a new 1.0-litre TSI turbocharged petrol engine. While that will probably make for an enticing drive, it's a sad fact that the current 1.2-litre Polo is a touch sluggish to drive, and the mechanically similar SEAT Ibiza has some refinement issues. On that basis, we'd go for the Rio - it's neatly styled, comfy, well made and lively to drive. And it comes with that seven-year warranty. It's a tough package to beat.

Let us know how you decide in the comments below.

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Hi Bill, glad we're of assistance - spread the word!

In answer to your question, it's something of a yes and no. Yes, you could potentially find a cheaper 5 Series by shopping somewhere other than a franchised BMW dealer, but why then try and buy a warranty from BMW? Part of BMW's second hand car warranty package is a full inspection of the vehicle and a check of all major components. Assuming that they would warranty your car unseen, there would almost certainly be a loading on the premium to reflect the fact that they are effectively insuring an unknown car against failure.

So, I would suggest one of two things - either stick with the full franchised BMW second hand package (which is actually pretty keenly priced once you factor everything in) or buy elsewhere and go to a third party for the warranty insurance. Mapfre is pretty much the only game in town in Ireland for aftermarket warranties at the moment, and it has a simple online application form so you can work out the cost of the warranty before you buy the car. Here's the company's website.

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Hi Francis,

Can I suggest then chopping it in for another Hyundai, this time an i40 Tourer? It's massively spacious so you won't (aside from the seat height) feel like you're trading down. It's also very comfy and, with your long-haul runs and high-ish mileage in mind, hugely economical. Drive the 1.7 115hp CRDi version gently and you should top 60mpg. 

If you don't fancy another Hyundai, then picking a similar estate from the Ford Mondeo, Opel Insignia, Volkswagen Passat or Peugeot 508 ranges should do the job just as well.

Let us know what you end up doing

Expert answer

Hi Steve,

That fault code indicates a wiring issue somewhere that may well be your problem, but would require a good auto electrician to sort out. 

However, before doing that, a known issue with that car causing similar problems is a faulty engine coolant temperature sensor that intermittently sends the wrong signal to the car's brain and causes all kinds of problems. It needs to be replaced and shouldn't cost the earth.