I have a Lexus RX 400h year 2005 which has just failed its MOT on the following:

  • rear subframe is corroded and seriously weakened.
  • rear wheel bearing is rough and has excessive play

It also has a number of advisories which we know will probably need doing within the next year which include:

  • rear suspension
  • rear brake discs and pads
  • both rear tyres are close to lega limit.

Firstly, is the car still safe to drive with the rear subframe being in such a poor state (it has corrosion and holes in it), would it be worth getting the fail work done to the car to get it through an mot with the other advisories that are listed that would more than likely need doing in the next year.

If so how much do you think it will cost? The rear subframe also seems impossible to get hold of at the moment. The car has also done just over 125k miles.

Thank you

3 Answers 3


The MOT report has an option to specify that the car is in such bad condition that it should not be driven at all, and the only way it will be allowed to leave the MOT test center is loaded onto a recovery vehicle at your expense (or it will be scrapped if you don't pay to remove it), so presumably your car isn't that bad!

However if it has failed its MOT, then strictly speaking it is illegal to drive it at all, except to move it to the place where you intend to repair it, and/or to get it retested. Bear in mind that the failure is recorded on the DVLA database, so if the police are doing spot checks on vehicles they will know about it, and if you are involved in an accident your insurance company will know as well. The fact that your old MOT certificate hasn't expired yet is irrelevant.

The advisories are just advisories. I have been getting advisories that my exhaust system is likely to fail the test soon for the last 5 years, and the old system is still on the car and just as good now as it was 5 years ago. Getting advisories depends on the examiner, and probably on how busy the test center is that day. But obviously "tires near the legal limit" will wear if you keep driving, and tires below the legal limit can be very expensive if they result in a prosecution.


MOT checks have a low risk tolerance, so it's possible your car is still safe to drive, but I wouldn't bet on it. Plus, you can't legally drive it now.

A good guide to whether a car is worth fixing is using insurance company repair to value ratios. Every company is different but a good working figure is that if the repairs are worth more than 70% of the car's value insurance companies would give you the value of the car rather than repair it. Some companies have a lower repair to value ratio and will only fix cars up to a 50-60% value, but I think 70% is a reasonable figure to use when deciding whether to repair a car that is your own. The reason you want a buffer of at least 30% is that estimates can be off by a large margin, especially if your mechanic finds things that need urgent repair as they dig into it.

So, get an estimate of what it will take to fix everything, including the suspension advisories (if they are taking your subframe off they'll be taking the suspension apart anyway), then see how it compares to the value of your car. From what I can see your car is worth about £3000 or so, you'd probably not want to put more than £2000 into it.

As for the rear subframe there seems to be a gazillion available on ebay, which is actually a reasonable place to find parts as long as you source them from a seller with good reputation.

  • But is £2000 to kerp it going a cheaper option than £9000 to replace it? And perhaps the tax has just been paid? And better the devil you know - buying a replacement could have lots of things about to go wrong...
    – Solar Mike
    Commented Jul 12, 2020 at 14:15
  • The insurance company valuation for 'write-off' isn't a like-for-like calculation, because they don't have to pay for a replacement car. It's just whether paying for an accident repair will be less for them than a write-off payout. Commented Jul 12, 2020 at 17:08
  • @WeatherVane, repair to value ratio is an objective, non opinion based answer to 'is it worth it to fix or not'. Insurance companies know a thing or two about repair costs and value.
    – GdD
    Commented Jul 12, 2020 at 17:14
  • You've missed my point: it isn't their car, and they have different aims. And it isn't "objective" because as you say yourself they all use different scales, making it "subjective". Commented Jul 12, 2020 at 17:15
  • @WeatherVane, I got your point, I just don't agree with you. I've been down this road several times and made the mistake of spending more money repairing my car than it was worth. I think the insurance company's way of looking at it makes sense.
    – GdD
    Commented Jul 12, 2020 at 17:18

It depends.

I have just had the rear suspension rebuilt on my car at a cost of just under 2k.

It was made in 2005 with 170k miles on it, but finding a good replacement would involve more money...

So, if you get a local garage to do the work then that is one price, if you go to a main dealer then it is a different price.

  • What sort of car do you have if you don't mind me asking. Yeah it would be with a local mechanic, I just don't know wherher it's worth doing it all or wherher it's just going to start turning into a money pit. The main thing at the moment is getting it through its mot but I have no clue what a rear subframe would cost and whether we would actually be able to get the part as the garage has said due to the type of car it is it could be really difficult to get hold of the part.
    – caarlaa123
    Commented Jul 12, 2020 at 10:31
  • A Jaguar X-Type estate. I ordered parts from the bay of fleas as parts locally for me are very expensive.
    – Solar Mike
    Commented Jul 12, 2020 at 10:47

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