Jaguar won't be competing in the entry level 316 petrol market which is the only 3 Series around that price (23,500 iirc?). Like for like comparison would be the 320d which definitely does not start at £23,500. Expect the XE to be around the £28,000 mark.
We have already been told by Jaguar not to expect them to compete on price. Expect lots more kit instead though...