Hello, I'm looking to change my car and would be grateful for some suggestions.

I drive over 15,000 miles/year, mainly motorway miles with a 270-mile each-way trip once a fortnight. My trusty 2012 Mazda 6 2.2d at nearly 200k miles is going from trusty to rusty, so time to think about replacing it. I average around 56mpg on the motorway, and do very little town driving. The other car in the family is a Renault Captur, which I enjoy driving but it's not been reliable unfortunately, as it doesn't like periods of not being driven, e.g. 3 weeks between being used.

My wish-list includes:
Good fuel economy at motorway speeds
Must be reliable car, cheap to run, and easy to obtain and fit parts
Boot big enough for 2 large suitcases
Must have space for a full-size or space-saver spare wheel, the foam stuff is useless if the tyre gets shredded on the motorway at
midnight.
I'd prefer small SUV/crossover, but not essential. Economy and reliability are the top factors.

My budget is in the £10k-£12k range though might go a bit higher for the perfect car. I'd be happy with another diesel, never had a problem with them, but would need to be Euro6 ULEZ compliant.

Thanks in advance!