The only one I know that members have used is Moneybarn, but I think they have a £5k minimum and quite a high rate and you will have to wait until the IVA is finished.
If you do secure finance before the end, you will need the prior permission of your IP.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014
We used moneybarn, and as per Foggys post, they do look at a minimum of a £5k car to finance, and it used to have to be less than 6 years old and have below 70k mileage. We were asked to put down a deposit, but you could put as much as you want down and this reduced the monthly repayments.
Their is also Carloans 4 u that could maybe help you.
Started IVA 27th Feb 2012 - Due to complete 27th Jan 2018 !!
Full & Final submitted and accepted 30th March 2015, paid 10th April 2015 - 3 yrs 1 month into IVA
Completion Certificate received- 30th April 2015!!
Is it a runaround you're after, could you miss a couple of payments and tag them on the end, with prior permission of IP of course. Or could a family member/close friend assist and you pay them back when your IVA has completed?
IVA final payment left the bank on the 26th January 2013...looking forward to a debt free future.